Orlando gunman Omar Mateen initially spoke in Arabic and declared himself to be an "Islamic soldier" during phone calls with emergency authorities as he killed 49 people, according to a transcript released by the FBI Monday.
"I'm in Orlando and I did the shootings," he told a 911 operator during his initial phone call from the Pulse nightclub in the early morning hours of June 12. The release offered few fresh details on the shootings.
The transcript was initially redacted to remove Mateen's pledge of allegiance to Islamic State and its leader, Abu Bakr al-Baghdadi. The Justice Department said in a statement as it released the full transcript that it was trying to be transparent while remaining sensitive to victims' families and not provide publicity for a terrorist group.
"I pledge allegiance to Abu Bakr al-Baghdadi may God protect him [in Arabic], on behalf of the Islamic State," reads the unredacted transcript of the 911 call, which authorities say lasted about 50 seconds.
House Speaker Paul Ryan criticized the decision to first release only the redacted version of the transcript.
"The attempt to selectively edit the record reflects a broader, more serious problem: this administration's continued effort to downplay and distract from the threat of radical Islamist extremism," Ryan said. "This is unacceptable. To defeat terrorism we have to be clear-eyed about whom we're fighting."
Mateen, who was eventually killed by police, also engaged in three separate phone calls with crisis negotiators, during which he said he carried out the attacks in response to U.S. bombings in Syria and Iraq, according to FBI officials.
The shooter threatened that "in the next few days, you're going to see more of this type of action going on," the FBI release said. He also claimed to be equipped with bombs, though authorities found none at the scene.
"While the killer made these murderous statements, he did so in a chilling, calm and deliberate manner," said FBI spokesman Hopper.
Investigators have still found no evidence Mateen was directed by a foreign terrorist group. But Hopper says the investigation could last "months and even years."
Investigators are still trying to determine Mateen's motive.
Mateen's father has said his son had voiced disgust recently at seeing men kissing in Miami. But some acquaintances of Mateen say he frequented the nightclub where he carried out the attack and visited gay dating sights on the Internet.
Reports have described Mateen as mentally unstable and angry, saying he frequently lashed out at minorities and beat his wife.
VOA National Security correspondent Jeff Seldin contributed to this report.