ISIS has claimed responsibility for the deadliest mass shooting in US history and says the gunman who took the lives of at least 50 innocent party-goers in an Orlando gay club was one of its fighters.  Shooter Omar Mateen, 29, from Port St. Lucie in Florida, opened fire at Pulse night club in the early hours of Sunday, killing at least 50 people and injuring 53 others.

This is the first time ISIS has claimed responsibility for an attack on US soil.  Shortly before the attack, Mateen, who was born in New York to Afghan parents, called 911 and pledged allegiance to ISIS leader Abu Bakr al-Baghdadi, law enforcement officials told NBC News. Below is the latest Updates Provided: