Stephen Paddock fired hundreds of rounds for a full 10 minutes from his Las Vegas hotel room on Sunday night as thousands of music fans ran for their lives outside, authorities said Wednesday evening.
Clark County Sheriff Joe Lombardo, who oversees the Las Vegas Metropolitan Police Department, gave the first detailed timeline of Sunday night's events, in which Paddock killed 58 people and injured 489 others before he committed suicide in his 32nd-floor suite at Mandalay Bay Resort and Casino. Lombardo said 317 of the injured had been released from hospitals.
Lombardo clarified that higher injury totals reported earlier turned out to have included people who had been counted twice or who had been injured in other ways. He said he was confident that the new total was accurate.
What is publicly known about the case expanded dramatically on Wednesday as investigators worked multiple locations across Nevada.
Photos: Nation Mourns Las Vegas Shooting Victims
Investigators were interviewing Marilou Danley, Paddock's roommate, who returned to the United States from the Philippines, her homeland, where Paddock had sent her two weeks earlier. She told investigators that she'd had no clue to what Paddock was planning, her attorney told reporters on Wednesday.
Authorities have said Danley, 62, is a person of interest in the investigation — a phrase that has no formal legal meaning but that is often used to indicate that investigators believe a person has critical information.
Lombardo also said police were still working to determine whether Paddock had any help or whether anyone knew about his plans. But he made it clear that he thought the gunman probably did have some kind of assistance, saying Paddock had prepared an elaborate escape plan that he could have pulled off alone only if he "had been a superhero."
"What we know is Paddock is a man who spent decades acquiring guns and ammo and living a secret life," Lombardo said. "Anything that would indicate this individual trigger point, which would cause him to inflict this harm, we're not there yet."
But "there are people who can help us understand this individual," he said.
Lombardo, meanwhile, confirmed that Paddock, 64, of Mesquite, Nevada, rented a room or rooms overlooking a "Life is Beautiful" music festival the weekend before. He didn't address speculation that Paddock may have been conducting a test run for Sunday night's attack or may even have intended to attack Life is Beautiful but called off the operation.
The accommodations in the ritzy Ogden hotel were rented through the online sharing site Airbnb, which is cooperating with the investigation, Lombardo said.
Another thread emerged Wednesday when multiple law enforcement officials told NBC News that they were trying to identify a mystery woman who had been seen with Paddock in the days before the massacre Sunday. The officials said they didn't know whether she had any connection to the attack.
On yet another front, Lombardo said multiple containers totaling 50 pounds of Tannerite were found in Paddock's car, along with about 1,600 rounds of ammunition. Tannerite is a material used to make exploding targets for firearms practice; it can also be used to make what are known as binary explosive devices. Authorities have previously said ammonium nitrate, which is intended for use as a fertilizer but can be used to make explosives, was also found in the car.
And for the first time, Lombardo gave a detailed recounting of what happened when on Sunday night, presenting a timeline that said Paddock fired his arsenal of weapons for 10 minutes.
The first shots were reported at 10:05 p.m. (1:05 a.m. ET Monday), the sheriff said. The first two Las Vegas police officers arrived on the 31st floor of the hotel, one floor below by 10:12, within only seven minutes, he said.
The gunshots stopped at 10:15 p.m., two minutes before the initially responding officers made their way to Paddock's floor. There, they found a security officer, who told them that he had been shot and pinpointed Paddock's location, Lombardo said.
Photos: Harrowing Photos Show Moments After Vegas Massacre
More officers began arriving, some of them clearing rooms and looking for anyone who had been injured, Lombardo said. Not knowing the extent of their risk, they worked slowly and methodically before breaching the door to Paddock's suite at 11:20 p.m., 65 minutes after the shooting had stopped, he said.
Officers found the suspect down on the ground, Lombardo said. They then breached the door to the second room in the suite, but no one was there, he said.
Police publicly announced that the gunman was down at 11:27 p.m., he said.