Gunman kills 50 in gay club rampage

FBI says mass shooting in Florida investigated as act of terrorism

Fifty people died and another 53 were injured when a gunman opened fire and seized hostages at a gay nightclub in Florida, police said on Sunday, making it the worst mass shooting in US history.

"We have cleared the building, and it is with great sadness that I share we have not 20 but 50 casualties in addition to the shooter," Orlando Mayor Buddy Dyer told a news briefing, raising the death toll from 20 previously.