Stephen Craig Paddock, the gunman behind the worst mass shooting in modern US history, checked into his Las Vegas hotel room on Thursday, three days before opening fire on a crowd of 22,000 from his hotel window.

Paddock fired what seemed to be an automatic rifle out the window of his hotel room on the 32nd floor of the Mandalay Bay Resort and Casino during the final act of the Route 91 Harvest country music festival, which took place in a lot across the Las Vegas Strip from the hotel.

Extended bursts of rapid fire can be heard on videos of the massacre. When the police entered Paddock’s room, they said, they found him dead with more than 10 rifles.

It’s unclear whether Paddock had the rifles with him throughout his stay. Some automatic weapons are legal in Nevada, though Mandalay Bay, in its policies, says weapons “are strictly prohibited” on the property. Paddock owns a home in Mesquite, Nevada, about an hour and a half away from the scene of the shooting by car.

The Daily Mail quoted a brother of Paddock, Eric, as saying that his family was “shocked” and “dumbfounded” by Paddock’s actions and that there were no indications as to a possible motive before the shooting.

Joseph Lombardo, the sheriff of the Las Vegas Metropolitan Police Department, told reporters that Paddock had used identification from Marilou Danley, a woman the police have identified as his roommate in Mesquite.

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The police indicated on Monday that Danley was out of the country and that they were not pursuing her in connection to the attack.

This post was updated at 3 p.m. ET.