LAS VEGAS (CBS SF) — The FBI said the shooter who killed 58 people and injured more than 500 others at a Las Vegas concert had no connection to an international terrorist group.

The announcement from Special Agent in Charge Aaron Rouse at a news conference Monday comes after the Islamic State group claimed responsibility for the attack without providing evidence.

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The extremist group claimed that the shooter was “a soldier” who had converted to Islam months ago. It has made exaggerated or false claims in the past.

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Authorities have yet to identify a motive for the shooting but say they believe 64-year-old Stephen Craig Paddock acted alone. He killed himself after the shooting.

Sheriff Joe Lombardo said the death toll from the Las Vegas shooting has risen to 58, with 515 people injured. A gunman opened fire on a Las Vegas country music festival Sunday night.

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The gunman opened fire from inside the Mandalay Bay Hotel and Casino. Authorities say 64-year-old Stephen Craig Paddock killed himself after the shooting. Police have yet to determine a motive.