Orlando Shooting: Partial content of Omar Mateen's 911 calls released

The Federal Bureau of Investigation (FBI) on Monday released partial transcripts of the 911 phone calls made by Orlando 'lone wolf' shooter Omar Mateen during the Pulse nightclub attack which left 49 people dead and 53 wounded in the worst mass shooting in US history.

"I let you know, I'm in Orlando and I did the shootings," the transcript read.

During the three phone calls with the police, Mateen pledged allegiance to the Islamic State (ISIS) and demanded that the US "stop bombing Syria and Iraq", as well as expressed solidarity with the Boston marathon bombers and an American suicide bomber in Syria, according to Xinhua news agency.

The transcripts noted that Mateen identified himself "as an Islamic solider", repeatedly spoke in Arabic and gave reference to God. However, FBI redacted the name of the ISIS and other extremists from the issued transcripts, saying that the bid is to avoid putting the victims through any more pain and so as not to further the extremist group's propaganda efforts.

The records showed that the 29-year-old gunman made the first call at 2:35 a.m. on June 12, while holding more than a dozen people hostage in the club's bathrooms. He spoke in Arabic when pledging allegiance to the "Islamic State" group during the 50-second call.

The shooter made the first call in "a chilling, calm and deliberate manner", said Ronald Hopper, FBI assistant special agent in charge in Orlando, during a news briefing on multiple TV networks.

Mateen later called 911 again and talked with a crisis negotiation team for 28 minutes, indicating there might be explosive devices on hostages.

That's when Orlando police chief John Mina gave the order for a SWAT team to make entry. They rescued several people by knocking out a hole in a bathroom wall with a battering ram before Mateen came out with a Sig Sauer MCX rifle as well as a handgun for a final and fatal gunbattle.

Asked if the gunfire killed hostages, Mina told reporters that the nightclub shooting deaths are "on the suspect and the suspect alone".

Meanwhile, the FBI official reiterated that there is no evidence that Mateen was connected to an Islamic terrorist group, saying that the gunman was "radicalised domestically", adding that neither the audio nor full transcripts of the shooter's phone calls will be released.

So far, the FBI has received more than 1,000 tips, conducted over 500 interviews and processed over 600 pieces of evidence in the Orlando shooting investigation.

After eight days of the shooting, as many as 18 wounded remain in hospital, four of them still in critical condition.