After she got medical treatment, Emma returned home, only to find Captain Hook.
(Flashback to Neal and Emma's wedding)
Emma and Neal were getting married in the Enchanted Forest when Captain Hook made it so that a pillar would fall over and crush Neal. Emma saw the pillar and she pushed Neal out of the way.
"Emma," Neal yelled with concern; but, it was to no avail. The pillar fell and it injured Emma.
(Back to the present timeline)
Emma was furious once she figured out that Captain Hook was the one who had injured her; so, she hurriedly crawled into the elevator. She (initially) started to close the elevator door; however, she left it open so that she could fight Captain Hook. Captain Hook complied and Emma stabbed Captain Hook in the back with a sword; however, Captain Hook popped back up and he laughed.
The police arrived to find a dagger-holding Emma in a bloody, sleeveless and white top and bloody flannel pants. The police also found the corpses of Regina, Robin and Maid Marian. Captain Hook was nowhere to be found.