ORLANDO, Fla. (CBSNewYork/AP) -- A television news producer said the Orlando nightclub gunman called into the station during the attack.
Matthew Gentili, a producer for local cable News 13, told CBS News that Omar Mateen called the station around 2:45 a.m. Sunday while he was slaughtering 49 people inside the gay nightclub Pulse.
"I answered the phone as I always do: 'News 13, this is Matt.' And on the other end, I heard, 'do you know about the shooting?'" Gentili said.
Gentili explained to CBS News that Mateen cut him off as he was replying.
"I'm the shooter. It's me. I am the shooter," Gentili said Mateen told him.
Gentili revealed that Mateen said he did it for the Islamic State of Iraq and Syria and then started to speak in Arabic.
"At the time, I didn't know what he was saying," Gentili told CBS News. "He was speaking so fast. But it was … he was speaking fluently. Whatever language he was speaking, he knew it. And he was speaking it very quickly. And that is when I said to him, 'Sir. Please. Speak in English, please.'"
Gentili added, "It was silent for a while. I asked him: 'Is there anything else you want to say?' He said no and hung up the phone."
The FBI did interview Gentili about the call.
Investigators are looking into the motives of Mateen, who attacked the Pulse dance club early Sunday, leaving 49 people dead. Mateen died in a gun battle with police.
On Wednesday, the FBI said it is still gathering evidence at the Pulse and poring through volumes of leads and tips about Mateen and those who knew him, and it put out a flier asking anyone with any information about the killer to contact the bureau.
"We need your help in developing the most complete picture of what he did and why he did it," FBI agent Ron Hopper said.
Investigators also are looking into his wife, 30-year-old Noor Zahi Salman.
Law enforcement sources tell CBS News there is video of Salman purchasing ammunition from a store with Mateen. Investigators also believe she drove with him to case the club.
A law enforcement source also said Salman told the FBI she tried to stop her husband from committing the attack. She told investigators they had been to the club at least once before.
Authorities have interviewed her twice and given her a polygraph test, CBS News reported.
Her romance with Mateen began online, according to a neighbor, and they were married on Sept. 29, 2011, near her hometown, according to public records. The couple has a 3-year-old son.
In addition, 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.
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 attack ended with the 29-year-old American-born Muslim being killed by a SWAT team.
Orlando is nearly a two-hour drive from Mateen's home in Fort Pierce, Florida.
"What I know concretely is that he was driving around that evening and visited several locations," Dyer said.
CBS2's Tony Aiello reported that Dyer said during the two-hour standoff that Mateen threatened to strap bombs onto hostages, but there's no evidence he actually had any explosives.
When asked exactly where Mateen visited, and whether the locations included theme parks as reported in news accounts, the mayor said: "I think it's been pretty accurately depicted on the news." He gave no further details.
Meanwhile, the FBI is also checking reports that Mateen had been a regular at the club and had used gay dating app before the shooting.
"He used to come in the bar about, on the weekends," said club patron Jim Van Horn.
Michael Bass, who operates the gay club "Revere" said he received a Facebook friend request from Mateen three days before the shooting.
"I saw that picture that morning of the incident -- I swallowed my tongue," Bass said.
Video footage of Mateen from a 2012 documentary shows him working as a security guard following the BP oil spill. In the footage, he seems skeptical of the clean up efforts.
"No one gives a s*** here," he said. "Everybody's just out to get paid."
On the day of the shooting, Mateen went to work as a guard in a gated community in Florida, CBS News reported.
The FBI said Mateen spoke with a 911 operator three times early Sunday morning and also pledged loyalty to the head of the Islamic State of Iraq and Syria on his last call.
Sources told CBS News Mateen also left a Facebook post pledging his allegiance to ISIS, all while randomly shooting into the crowd.
"This is a methodical, time sensitive, time intensive work that includes trajectory analysis and crime scene mapping," Ron Hopper, the FBI's assistant special agent in charge, said.
Orlando will welcome President Barack Obama on Thursday. The White House said he wants to grieve with families of the 49 killed, comfort survivors and express the thanks of the nation to the first responders.
The U.S. attorney said many threats have been made against Muslims in Orlando and each has to be investigated thoroughly. He added that's diverting resources from the investigation.
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