ORLANDO, Fla. (AP / FOX 11) - Orlando mourned the 49 people slaughtered in the attack on a gay nightclub, as the White House and the FBI portrayed the killer Monday as an apparent "homegrown extremist" who espoused support for a jumble of often-conflicting Islamic organizations.
The last of the bodies were removed from the nightclub late Sunday, and vigils and makeshift memorials to the victims of the deadliest mass shooting in modern U.S. history began to take shape as counterterrorism authorities delved into gunman Omar Mateen's background and defended their handling of their previous contacts with him.
Wielding an AR-15 semi-automatic rifle and a handgun, Mateen, a 29-year-old American-born Muslim, opened fire at the crowded Pulse Orlando club early Sunday. He was killed in a gun battle with a SWAT team after police used explosives and a small armored vehicle to punch a hole in a wall and allow dozens of club-goers to escape, police said.
The tragedy shocked the nation and cast a pall over Orlando, known all around the globe as the home of Walt Disney World and other theme parks.
"We will not be defined by the act of a cowardly hater," Mayor Buddy Dyer vowed.
FBI Director James Comey said that Mateen had "strong indications of radicalization" and was probably inspired by foreign terrorist organizations.
He said Mateen called 911 around the time of the attack and not only pledged loyalty to the Islamic State but also expressed solidarity with the Tsarnaev brothers who carried out the Boston Marathon bombing and a suicide bomber who died on behalf of the al-Nusra front, a group at odds with the Islamic State.
In the past few years, Mateen also expressed support for both al-Qaida and its enemy Hezbollah, Comey noted.
The FBI investigated Mateen for 10 months beginning in May 2013 after he was said to have made inflammatory remarks in support of terrorists.
Comey said investigators introduced him to confidential sources, followed him and reviewed some of his communications, but Mateen claimed he made the remarks in anger because co-workers were teasing and discriminating against him because he was Muslim. The investigation was brought to a close.
As for whether the FBI should have done anything differently, "so far the honest answer is, 'I don't think so,'" Comey said.
At the White House, President Barack Obama said there is no clear evidence so far that Mateen was directed by the Islamic State. He said Mateen was inspired by radical information over the internet, calling it another apparent example of "homegrown extremism."
Meanwhile, a steady stream of people filed through a makeshift memorial about a mile from nightclub. It consisted of dozens of bouquets and candles.
Just after noon about 300 employees of Red Lobster -- some in business suits, some in chef uniforms -- paraded, walking two-by-two across the street to a park, each carrying a red or white carnation.
Counterterrorism experts have been warning in the past few years about the danger of so-called lone wolf attackers who act in sympathy with extremist groups like the Islamic State but are not directed by them.
Despite the 911 call from the club, Mateen's intentions seemed to become murkier when his Afghan immigrant father suggested another motive: anti-gay hatred. The father said his son got angry a few months ago when he saw two men kissing in Miami.
Also, Mateen's ex-wife attributed the violence to mental illness, saying he was bipolar and abusive toward her.
Obama said investigators are still looking into the killer's motivations and considering all possibilities, noting that Muslim extremist groups like the Islamic State have been known to target gays.
The Islamic State's radio called Mateen "one of the soldiers of the caliphate in America." Al-Bayan Radio, a media outlet for the extremist group, hailed the attack, saying that it targeted a gathering of Christians and gays and that it was the worst attack on U.S. soil since 9/11.
The statement gave no indication of whether the group planned or knew of the attack beforehand.
Mateen's father, Seddique Mir Mateen, told reporters Monday that the massacre was "the act of a terrorist," and added: "I apologize for what my son did. I am as sad and mad as you guys are."
He wouldn't go into details about any religious or political views his son held, saying he didn't know. Asked whether he missed his son, he said: "I don't miss anything about him. What he did was against humanity."
Thirty-nine of the dead were killed at the club, and the others died at hospitals, the mayor said. Authorities were still notifying victims' families Monday.
At least 53 people were hospitalized, including five in grave condition, meaning the death toll could rise.
The previous deadliest mass shooting in modern U.S. history was the 2007 attack at Virginia Tech, where a student killed 32 people and took his own life.
Mateen bought at least two guns legally within the last week or so, according to Trevor Velinor of the Bureau of Alcohol, Tobacco and Firearms.
Mateen exchanged gunfire with 14 police officers at the club and took hostages at one point. In addition to the assault rifle and handgun, he had a weapon in his vehicle, police said.
Police Chief John Mina said officers held back for some time because Mateen indicated he had a bomb vest. About 5 a.m., authorities sent in a SWAT team to rescue the remaining club-goers, Mina said.
Associated Press writers Eric Tucker in Washington, Terrance Harris, Mike Schneider and Tamara Lush in Orlando and photographer Alan Diaz in Fort Pierce, Florida, contributed to this report.