The Islamic State (IS) terrorist group says a gunman who on June 12 carried out the deadliest mass shooting in U.S. history -- killing 49 people at a gay nightclub in Orlando, Florida -- was one of its "soldiers."
Earlier reports had listed the number of dead as 50, but Orlando police authorities on June 13 revised that figure to 49, plus the shooter. Paul Wysopal, an FBI special agent, said 48 victims had been identified and 24 victims' families had been notified.
U.S. law enforcement officials identified the gunman as Omar Mateen, 29, a U.S.-born citizen of Afghan descent, and said he had called an emergency police-dispatch operator just before the killings and proclaimed his allegiance to IS.
Mateen was shot dead by police who stormed the Pulse nightclub three hours after the killings began there.
"One of the caliphate's soldiers in America carried out a security invasion where he was able to enter a crusader gathering at a nightclub for homosexuals in Orlando, Florida...where he killed and injured more than a hundred of them before he was killed," IS said in a broadcast on its Al-Bayan Radio.
The IS-linked news agency Amaq, meanwhile, said on June 12 that the attack had been "carried out by an Islamic State fighter."
Despite the statements, however, IS has not officially claimed responsibility for the attack.
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Police said the attacker opened fire with an AR-15 assault rifle and a handgun in the nightclub shortly before 2 a.m., and then held a group of club patrons hostage for three hours before he was killed in a shoot-out.
Fifty-three people were wounded, and many remain in critical condition with multiple gunshot wounds.
U.S. President Barack Obama called the attack "an act of terror and an act of hate."
Obama said the authorities are "still learning all the facts" and that an investigation was continuing, but authorities had "reached no definitive judgment on the precise motivations of the killer."
Statements of sympathy and condemnation have been pouring in from around the world.
In a statement, Afghan President Ashraf Ghani condemned the attack, saying that "targeting civilians is not justifiable under any circumstances whatsoever," while Chief Executive Abdullah Abdullah told the country's cabinet that the incident "tells us that terrorism knows no religion, boundary, and geography. Terrorism must be eliminated."
Paris city hall said the Eiffel Tower will shine in the colors of the rainbow on the night of June 13 to honor the victims of the Orlando tragedy. U.S. and rainbow flags will fly. The rainbow flag is the symbol of the LGBT community. In November, 130 were killed when IS extremists carried out attacks on a music hall, restaurants, and bars in the French capital.
Queen Elizabeth II and Prime Minister David Cameron have sent messages of condolence from Britain, while German Chancellor Angela Merkel has said it's important to continue with "our open, tolerant life" following the Orlando attack.
China's President Xi Jinping has telephoned President Obama to express his condolences over the shootings.
In London, gay bars in the Soho area plan to close for one hour late on June 13 for a "London stands with Orlando" vigil.
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Despite Mateen's call expressing allegiance to Islamic State, and despite claims by the IS group that Mateen was their "soldier," U.S. officials said they had no conclusive evidence of any direct connection with foreign extremists.
It was not immediately clear whether the attacker received instructions and training from the radical group or merely had been inspired by the group's militant, extremist, ideology and had acted alone.
U.S. Representative Adam Schiff, the top Democrat on the House Intelligence Committee, said late on June 12 that investigators had not yet found any evidence of direct communication between Mateen and the IS or any other international terrorist organization.
Schiff said it was possible that Mateen was self-radicalized but not "under the command and control" of IS.
Mateen, the son of Afghan immigrants to the United States, was born in New York and moved to Florida at a young age with his parents.
He had been an armed guard at a gated retirement community, and worked for the global security firm G4S for nine years. G4S said he had cleared two company background screenings, the latest in 2013.
G4S said in a statement that it was "cooperating fully with all law enforcement authorities, including the FBI, as they conduct their investigation."
G4S has 623,000 employees worldwide and describes itself as "the largest security solutions provider in the world," on the company website.
Florida state records show that Mateen held a firearms license since at least 2011. Authorities also say Mateen legally purchased at least two firearms within the past week or so.
Mateen married a woman in March 2009 named Sitora Alisherzoda Yusufiy who was born in Uzbekistan and immigrated to the United States. They became separated after just a few months and were legally divorced in 2011.
Yusufiy told the media she had met Mateen online and moved to Florida where she lived with him from April to August 2009. She said he beat her regularly.
"He was mentally unstable and mentally ill," Yusufiy told reporters in Boulder, Colorado.
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The suspect's father, Seddique Mateen, said early on June 12 that he believed his son was motivated by hatred of homosexuals -- not by his Muslim religion.
Seddique Mateen said his son got angry when he saw two men kissing in public in Miami several months earlier in front of his 3-year-old son.
"This had nothing to do with religion," Mateen's father told the media. "I don't know what caused it," Seddique Mateen said. "I never figured out that he had a grudge in his heart...I am grief-stricken."
"We are saying we are apologizing for the whole incident," Seddique Mateen said. "We are in shock like the whole country."
The FBI said its agents twice investigated Mateen for alleged Islamist links but closed those cases after interviewing him.
Special Agent Ronald Hopper said Mateen was first investigated in 2013 after he made inflammatory comments to co-workers alleging possible ties to terrorists.
In 2014, the agency looked into potential ties between Mateen and Moner Mohammad Abusalha, a resident of Fort Pierce, Florida, who carried out a suicide truck-bomb attack in Syria and had appeared in a video released by the Al-Qaeda-linked Al-Nusra Front.
Hopper said the FBI determined that contact between Mateen and Abusalha "was minimal and did not constitute a substantive relationship or a threat at that time."
With reporting by RFE/RL's Radio Mashaal, AP, Washington Post, NBC, Reuters, AP, AFP, BBC, and the Orlando Sentinel