Survivor of the Orlando Massacre Alejandro A. Francisco has penned an articulate and thought-provoking letter to killer Omar Mateen which has caused waves across the world.

Survivor of the Orlando Massacre Alejandro A. Francisco has penned an articulate and thought-provoking letter to killer Omar Mateen which has caused waves across the world.

Federal investigators are examining possible motives for the massacre of 49 people in a Florida nightclub - the worst mass shooting in modern US history.

US authorities are investigating whether anyone helped the gunman who massacred 49 people at a gay nightclub in Orlando, but said they did not believe anyone connected to the shooting posed a current danger to the public.

Witnesses to America's worst mass shooting described their efforts to flee the scene.

Gunman Omar Mateen, who killed at least 50 people in a gay nightclub in Florida, was mentally unstable and had a history of using steroids, his ex-wife said.