(CNN) – The gunman who killed 50 people at an Orlando nightclub pledged allegiance to ISIS and mentioned the Boston bombing in a 911 call, according to a U.S. official.

Suspect Omar Mateen made the call more than 20 minutes into the attack, a law enforcement official said.
Authorities haven’t officially released the gunman’s name, but several law enforcement officials have identified him to CNN as Mateen.
The 29-year-old, who was killed by police, is from Fort Pierce, Florida, the officials said.
Local and federal bomb squad teams entered Mateen’s apartment there Sunday afternoon as authorities tried to piece together details about the attack. Investigators haven’t revealed what they found there.
The gunman was born in New York, a U.S. official said, and his parents are originally from Afghanistan.