Fifty people are now known to have died in Saturday's shooting in a gay nightclub in Orlando, Florida, and a state of emergency has been declared, the city's mayor Buddy Dyer has said.
The gunman, named by officials as Omar Mateen, was killed after taking hostages.
Another 53 people were injured in the shooting at the Pulse club.
It is the worst mass shooting in recent US history. Police described it as an act of terrorism.
Officials said the killings were likely to be ideologically motivated, though there was no information that the gunman was associated with a particular group.