Once upon a convient order of events,
It started on a single campus, a high school campus (who knew anything happened there but "Learning".) Now it just so happens that L decided to sit on a bench by a HUGE tree, Light was of course staggering over to L. A few days ago he found out that L was of great intelligence and he should approach him, it was a difficult task. Just sayin'.
Mello was actually in the HUGE tree and was sitting in his crossed-legged laid-back pounding on the chocolate that probably shouldn't even be on campus was coming to stall Mello by being there, because Matt had asked him (nicely) to, since he was busy doing things that could get him seriously injured or killed by a certain blonde. Even though no one knew it, Beyond Birthday was also there, to "Watch" after Lawliet.
Now there was an alien spaceship passing by Earth, don't ask how no one knew it. No one ever knows it. That's how it works and if it isn't they keep it to themselves. These very borded aliens had that in English that sounded like this, "wanna give some random people super powers?" said Ryuk "why not" said Rem. "ZAAAAAAP!" they had a lot of fun and shot Earth a couple of times with some very special radiation of some sort.
Guess where a nice beam hit? Yup. That HUGE tree, to a bystander it would have looked like green lightning shot out of a cloudless sky, we know better.
Or do we?