Law enforcement officials are still attempting to piece together a motive for one of the deadliest mass shootings in modern history, CNN reports.

The gunman, Stephen Paddock, 64, took the lives of 59 festival attendees and injured nearly 530 late Sunday night.

While authorities found several more weapons in the hotel room Paddock checked into at the Mandalay Bay Resort and Casino, they are still in search of a motive.

Several vigils were held in memory of those who lost their lives Sunday, with community members gathering in Reno, Las Vegas, the University of Nevada’s campus and the Nellis Air Force Base.

After responding to reports of a gunman, a team of six officers searched the hotel floor by floor Sunday before determining the shots were coming from Paddock’s two-room suite on the resort’s 32nd floor, said Joseph Lombardo, Las Vegas Metropolitan Police sheriff.

Lombardo also disclosed that Paddock was alive when he first interacted with the officers. The sheriff said the gunman fired at them through the door, shooting a security guard in the leg. The door was broken down by a SWAT team, but Paddock had already killed himself, he said.

Investigators believe the firearms used in the massacre were purchased legally and initial reports suggest at least one rifle was altered to operate as an automatic weapon, officials said.

Story developing.