Roundup: White House calls nightclub shooting "homegrown extremism"; Orlando in mourning

Memorials and vigils were held in Orlando, Florida, after 49 lives perished in a shooting massacre in a gay nightclub, as the White House on Monday called the shooting "homegrown extremism."

As "the City Beautiful" sank into grief after waking up to the deadliest mass shooting in U.S. history, authorities on Monday offered a detailed account of the battle to end the carnage and started to look into the motives behind the killer.

Wielding an AR-15 semi-automatic rifle and a hand gun, Omar Mateen, a 29-year-old Afghan American, walked into the packed Pulse nightclub and opened fire on the crowds at around 2:00 a.m. local time (0600 GMT) on Sunday. He then took several hostages and holed himself up.

More than three hours later, Mateen emerged through a hole in the building that a police armored vehicle had punched earlier to let clubgoers escape. He was later killed during the gun battle with SWAT forces, said Orlando Police Chief John Mina at a morning news briefing on Monday.

The lone gunman did pledge allegiance to the Islamic State (IS) and tried to negotiate with police during the attack, Mina said.

"He was cool and calm when he was making those phone calls to us," Mina said. "We had a team of crisis negotiators that did talk to the suspect just trying to get as much information as possible ... He really wasn't asking for a whole lot. We were doing most of the asking."

The police officer also disputed the rumors that there were multiple shooters, and confirmed that "the one shooter, Omar Mateen, is dead."

Director of Federal Bureau of Investigation James Comey said on Monday there were strong indications of radicalization by the shooter and of potential inspiration by foreign terrorist organizations.

However, "it is also not entirely clear at this point just what terrorist group he aspired to support," said Comey at a briefing in Washington.

According to Comey, the shooter made three 911 calls, in which he mentioned not just allegiance to IS, but also solidarity with two suspects of the Boston Marathon bombing and a Florida man who died as a suicide bomber in Syria for al-Nusra Front, a group actually in conflict with IS.

"The bombers at the Boston Marathon and the suicide bomber from Florida were not inspired by ISIL, which adds a little bit to the confusion about his motives," Comey said.

At the briefing in Orlando, a FBI agent also clarified that the total number of nightclub victims was 49 instead of the previously reported 50, a number that counted the shooter himself as a victim.

"The shooter is not a victim," FBI Special Agent in Charge Paul Wysopal said.

At least 53 people were hospitalized, including five in grave conditions, suggesting that the death toll could further rise.

The tragedy, the deadliest terror attack since the 9/11 terror attacks in 2001, shocked the whole nation and brings into focus the specter of homegrown terrorism that the U.S. authorities have been worrying about.

On Monday, U.S. President Barack Obama called the shooting "homegrown extremism," and said it appeared that Mateen was motivated by extremist propaganda online as no evidence was found about his direct link with radical groups.

"As far as we can tell right now, this is certainly an example of the kind of homegrown extremism that all of us have been so concerned about for a very long time," said Obama at the White House.

"It does appear that at the last minute, he announced allegiance to ISIL," said Obama, referring to an acronym of the extremist group the Islamic State (IS) based in Syria and Iraq. "But there's no evidence so far that he was, in fact, directed by ISIL."

As authorities are working to piece together details surrounding the motives of the killer, people in Orlando mourned the dead and tried to stay strong in front of the tragedy.

Flags in front of all venues were flying half-staff, and every electronic billboard on the expressway was showing the same message: Pray for Orlando.

At the OneBlood blood bank, dozens of people lined up to donate plasma. Some of them came as early as 9 a.m.(1300 GMT) on Sunday.

According to a blood bank worker, the blood bank was overwhelmed by more than 2,000 people who had registered to donate on Sunday. The bank had to ask donors to come back later over the next few days.

After nightfall, survivors, friends of the victims and members of the city's LGBT community gathered by the city's iconic Lake Eola to hold a vigil on Sunday for the deceased and injured.

"This is probably the most difficult day in the history of Orlando," said Orlando Mayor Buddy Dyer in a news conference on Sunday.

"We need to support each other. We need to love each other, and we will not be defined by a hateful shooter. We will be defined by how we support each other," Dyer added. Endit