ORLANDO (CBSNewYork/AP) — The Orlando nightclub gunman warned on his Facebook of more attacks from the Islamic State of Iraq and Syria in the United States, according to CBS News.

CBS News reported Omar Mateen posted on Facebook before killing 49 at the gay nightclub Pulse: “You kill innocent women and children by doing us airstrikes..now taste the Islamic state vengeance. In the next few days you will see attacks from the Islamic State [ISIS] in the usa.”

Authorities said Mateen pledged allegiance to the terror group when he called 911 during the shooting. He also called an Orlando television news station during the attack and said he pledged allegiance to ISIS.

ISIS has claimed responsibility for the attack.

“We begin from America, where Allah has enabled brother Omar Mateen, one of the soldiers of the Caliphate in America, to carry out a raid where he was able to infiltrate a Crusaders’ gathering at a gay night club in Orlando, Florida,” a report from al-Bayan, the group’s official radio station, said.

CBS News’ Paula Reid reported the FBI is characterizing the mass shooting as a hate crime and a terror attack.

A U.S. official said the FBI has determined that nightclub Mateen was in the area of Disney World at some point before the attack unfolded, though it’s unclear for what purpose.

The official briefed on the investigation who was not authorized to discuss the matter publicly and spoke Wednesday on condition of anonymity.

Orlando Mayor Buddy Dyer said Mateen drove around the Orlando area Saturday evening, going from one place to another, before he opened fire at the gay nightspot about 2 a.m. Sunday.

The FBI is investigating to what extent Mateen’s family members may have known he was looking to commit a violent act and did nothing to stop it, a law enforcement source told CBS News.

U.S. Attorney Lee Bentley repeatedly refused to say whether any charges might be brought against anyone. He said authorities are talking to hundreds of people and investigating everyone associated with Mateen, including family, friends and business associates.

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