Omar Mateen, the Afghan-origin gunman who killed at least 50 people at a gay nightclub in Orlando in US' deadliest mass shooting incident, pledged allegiance to ISIS in a phone call to emergency number 911 during the attack.
Omar Mateen, 29, walked into a gay nightclub in Orlando, Florida on Sunday and carried out the deadliest mass shooting in United States history, killing 50 innocent people before being shot dead in a standoff with the police.
