CAIRO/WASHINGTON (Reuters) - Islamic State claimed responsibility for a shooting in which a 64-year-old American man killed at least 58 people and wounded at least 515 in Las Vegas, but U.S. officials said there was no evidence so far linking the gunman to any international militant group.

In its claim, Islamic State said the gunman had converted to Islam a few months ago, according to the group’s news agency, Amaq.

U.S. officials said American security agencies were examining the claim of responsibility.

“The Las Vegas attack was carried out by a soldier of the Islamic State and he carried it out in response to calls to target states of the coalition,” Amaq news agency said in reference to the U.S.-led coalition fighting the group in the Middle East.

In a later statement from Islamic State, the militant group referred to the Las Vegas attacker by a nom de guerre of “Abu Abd al-Bar al-Ameriki.”

U.S. authorities said the gunman, who lived in a retirement home in Mesquite, Nevada, and was armed with more than 10 rifles, opened fire on a Las Vegas country music festival on Sunday night from a 32nd-floor window.

The man, identified by police as Stephen Paddock, killed himself before police entered the hotel room he was shooting from, police said.

Two senior U.S. government officials told Reuters that Paddock’s name was not on any database of suspected terrorists. There was reason to believe that Paddock had a history of psychological problems, one official said.