Live blog: Mass shooting at Orlando gay nightclub is worst in history

(CNN)A gunman killed 50 people and wounded at least 53 at a gay nightclub in Orlando, Florida, early Sunday, marking the deadliest mass shooting in U.S. history.

Key developments:
  • The gunman has been identified as Omar Mir Seddique Mateen, 29, of Fort Pierce, Florida. He was a U.S. citizen born in New York to parents from Afghanistan.
  • The shooter called 911, pledged allegiance to ISIS and mentioned the Boston Marathon bombers.
  • There were 300 to 350 people inside Pulse club during the shooting; 39 people and the shooter were pronounced dead at the scene.