A number of people were reported to have shot early on Sunday at a gay nightclub in Orlando, Florida, local media said.
The violence erupted at the Pulse nightclub, which urged patrons in a post on its Facebook page to "get out" and "keep running."
Local media reported that a number of people, ranging from seven to as many as 20, had been shot but there were was no confirmed fatalities. Several patrons posted on social media that a gunman was holed up inside and was holding hostages.
Police could not be immediately reached to verify the reports. Video posted online showed a large response by police and emergency vehicles outside the nightclub