Flame. That was the first thing he thought.
The second was shadow - stumbling up, the Elf sprinted into the ruins of a nearby building as a Balrog of Morgoth thundered down the street in pursuit of a score of Gondolindhrim. They were escorted by a trio of disheveled warriors, two with their spears and the third wielding a longbow. Utilizing his Elf-eyes, he saw that, from the fan of purple feathers upon his helmet, the archer was of the Folk of the Swallow - the finest the City could offer.
The archer turned about, pulled the arrow to his ear, whispered under his breath and let fly a shot. It soared through the smoky air and, right before impacting the Balrog's face, lit with a white flame. It exploded on contact, but to no avail. The turned Maiar barreled forward, and unleashed his rancour.
A pillar of flame overcame the lone bowman, and continued on into the crowd of Elven civilians. Their pained screams were drowned out by the roaring fires. The two spearmen were cooked alive in their maille, which was itself unwrought from the heat.
The Balrog continued down the street, its' shoulders shattering through the marble buildings upon either side.
Breathing heavily, the Elf gathered his wits. He'd been one of the lucky ones - stationed on the wall in full dress. He'd been girt with spear, shield, and longsword. He hadn't opted for a bow - having never been skilled with such a device of war. He'd been fully dressed in armour as well - a long coat of Elf-maille, greaves, and vambraces along with a tall helm. Due to his status among the House of the Golden Flower, he wore a brooch of similar appearance on his neck.
The Guard had been light that day, due to a holiday - all the folk of Gondolin were upon the wall, in the finest raiment in their possession. Banners were floating in the wind, minstrels were singing, and Elf-maids laughing. All were awaiting for the rise of the Sun.
And then it came, arising in the East - but a second light burst forth in the North.
The army of Morgoth - Orcs, Dragons, Balrogs, Wolves, infernal machines of war, all of them innumerable came running to the great Wall of Gondolin, burning the ground as they came. Reaching it, they then loosed their wrath upon the gathered Gondolindhrim.
Many were in the first moments slain - but the Wall held and the Guard proved their worth. Arrows soared from either side, tongues of flame split the air, and battle was joined.
For a time it seemed like a fair fight - the Children of Gondolin were numerous, their weapons well-forged, and their tactics honed to nigh-perfection over four hundred years.
But then a Balrog came to the Wall, and unhindered itself of physical bonds - a great storm of shadow and flame erupted and overcame the wall. The Wall was broken, and an entire section fell to the awesome power of a Maia. Fortunately, the Balrog was itself spent, and buried amongst his ruin.
All the Servants of Morgoth then picked their way through the debris and bodies, with Gothmog Lord of Balrogs at the head.
The Elf had been stationed at that point in the wall, and had been thrown far by the casting out of the Balrog. He'd lost his spear and shield upon landing, as well as his helmet. Blinking rapidly to clear his vision, the Elf checked himself and found that he still possessed his longsword. Releasing a breath he hadn't known he'd been holding, he drew the straight-bladed weapon and sprinted into a side alley.
Into a quintet of raiding Orcs.
The Orcs had been busy hoarding precious things from the nearby houses, and so were not aware of the Elf until he was among them. Screeching wildly, the Orc-chief swung out with his scimitar - but it was a wild blow and the Elf easily sidestepped it. He stabbed forward and calmly ran cold steel through the wretch.
The other four were upon him then, when a hail of arrows met them. The volley tore easily through their poor armour, and brought the beasts down quietly.
One survived, though and gripped onto the Elf's leg. Cutting down, he severed its' hand and head in the same motion.
Turning to his saviours, the Elf saw that they were three Elves - two Folk of the Heavenly Arch and the third also of the Golden Flower.
Greeting them, the Elf spoke quickly, "There is much to do. We must reach the Lord Glorfindel."
The others nodded, and one of the archers answered, "'Tis a dark day, indeed. And the Sun herself is just newly arisen."
"Then we must maintain her flight," spoke the third.

The four Gondolindhrim hurried towards the City Centre, weapons drawn or nocked, doing their best to creep unseen through side alleys.
The situation was indeed grim - the hordes of Orcs and their leaders - Dragons, Balrogs, Trolls - had completely taken the lower levels of the City, and were slaughtering their way to the upper ones. Smog and dragon-fumes chocked the air, and the Sun could not be seen.
Coming to a dead end, they turned about and realized they were in the middle of a vicious melee.
Hundreds, if not thousands, of Orcs and Wolves were encircling a group of Elven warriors - there must have three score at the most. Strangely, they wielded none of the standard gear of war of the Gondolindhrim - no spears, shields, swords, or bows were seen amongst their ranks. Instead, each bore a war hammer in size and make enough to rival the Naugrim of Belegost themselves. With these they smote their attackers, and in seconds the greater numbers of the Orcs were rendered useless. A second wave charged them, but to no avail. And another. And another.
One of the archers stepped forward and said, "We must aid them. Against such odds, their fortitude will not suffice"
But the other Elf, of the Folk of the Golden Flower, replied, "Such a deed would be folly. The yrch have no chance here. For tis the House of the Hammer of Wrath."
The archer appeared awestruck, nodded, and then lowered his bow.
The Elf continued, "Only some greater evil will smite them."
As if this was to serve as a heralding, a great beast lurched from down the street. Its' scales rippled like that of a fish; and yet they were imperfect. Patched and miswoven in places, its' monstrous hide reflected the inner fea of the being - tortured, ugly. Seeing the stalemate ahead of it, the abominations' eyes gleamed with a sinister intelligence, and it roared forth a challenge. The Folk of the House of Rog stared down the Drake, and cried out in one voice, fair yet terrible, "Aure entuluva! Day shall come again!" The two enemies - Drake and Elf - charged. The meeting of their rancour was like a thunder in the mountain-vales of Thangorodrim. Orc and Wolf were scattered aside or trampled beneath the combined onslaught. Together the two foes clashed - neither gaining nor losing ground. But despite the ferocity and flame of the monstrosity, it was all for naught. For he was not of the closest kin to Glaurung Father of Dragons, and his inner flame was chocked out by his own stinging blood. Enclosed in a ring of strong hammer-blows, the wyrm fell to the valour of Rog's Folk. But they were not yet finished; gathering their forces, the House of the Hammer of Wrath barreled down the street, and out of sight of the four Elves.
One of the bowmen spoke, "With such fervor in war, they go as if to win back the gates."
And the sentry spoke for the first time since their meeting, "Or to win a doom worthy of song."
And the bowmen answered, "Or for those that will sing it."

A great Orc roared beastily and swung his bladed club at the sentry's face. The Elf ducked, swung his sword outward, and into, the Orc. The blade was embedded in it's belly, pinning the spilled entrails painfully in place. Pulling it upward, the longsword cut through the Orc's chest cavity and came out of its right shoulder blade. It groaned and fell to the ground.
The Elf wiped a spot of black blood from his cheek, as it had spattered upon his impalement of the beast. It burned, but he ignored it and dodged a wild strike from another Orc. One of the archers dealt with it, firing an arrow into it's temple at close range.
They'd been ambushed in the back alleys by no less than a dozen of Orcs, and were hard-pressed to resist their bloodlust.
The other Elf of the Golden Flower stabbed forward with his spear, catching an Orc in the neck. Gripping the shaft at his, bladeless, end, he pulled the spear out of the ruined Orc's body and swung it in a wide arc, slashing the quintet of Orcs that had encircled him in many places. They cried out and grabbed wildly at their falling limbs, but were finished quickly by either the spearman or his companions.
They soon made short work of the raiding party, but could not tarry; the losses were not even marginal of the army that was currently occupying the City of Seven Names.
None of the Elves were wounded yet, and so continued on their way, South and East, to the Tower of Turgon the Wise, High-King of the Noldor.
Several hours passed, with nothing of significance occuring - largely due to their avoiding of combat. Over time, though, other refugees joined them, of various Houses; the Tower of Snow, Harp, and Tree were all represented. Altogether, they formed a company of twenty-three individuals.
The din of battle grew closer. The howls of Wolves, roars of Dragons and other more sinister evils became more distinct. Turning into one of the main streets, the group of Elves beheld full-out war.
The phalanx of the King held the last Gate. Eight ranks of spearmen stood in even formation, glittering in their burnished maille like the light of the Sun. Archers of the House of the Swallow were scattered behind them, taking precision shots at their leisure into the horde of enemies before them. Further behind them stood an orderly regiment of archers of the Heavenly Arch, who sent periodic volleys of steele into the gathered mass of Orc. Skirmishers from the House of the Fountain, led by Etchelion Lieutenant of the Tower, held the hordes at bay before the pike-wall.
Descrying a weak point in the Enemy's lines, the former sentry turned to his fellows.
"Let us join our comrades." With that he turned, drew his longsword, and lifted a recovered shield.
Throwing his sword into the air, he caught it and charged into the fray, friends behind and foes ahead.
"Aure entuluva! Day shall come again!"