Almost three days after the deadliest shooting in modern U.S. history, authorities are trying to piece together what happened on the fateful night of the attack but were still at a loss to offer a motive for the massacre.

The Las Vegas Metropolitan Police Department in a press conference Wednesday revealed a timeline of Sunday's attack at the Route 91 Harvest Festival near the Mandalay Bay Resort, and also revealed that the shooter, Stephen Paddock, planned to survive the attack.

Speaking to reporters Wednesday night, Clark County Sheriff Joe Lombardo said he had seen evidence that Paddock planned to survive and escape his attack on Sunday. However, Lombardo did not clarify what the evidence was.

Lombardo also said the shooter had rented an apartment overlooking the Life is Beautiful Festival that took place in the city the previous weekend.

The sheriff also stated about Paddock: “More than 100 investigators have spent the last 72 hours combing through the life of 64-year-old Stephen Paddock. It still remains unknown what led Paddock to go on a rampage. We haven’t found much about this guy; a lot of people live on social media, but he doesn’t.”

“We are trying to prove his intent or understand his intent and the history associated with this and whether or not he has any accomplices,” Lombardo added .

FBI Deputy Director Andrew McCabe told CNBC on Wednesday that the lack of a clear motive was a "surprise" in the shooting.

"This one is somewhat different than many of the ones we've dealt with in the past, because we don't have any immediately accessible thumbprints that would indicate the shooter's ideology or motivation, or really what compelled him to get there," McCabe said

Lombardo also revealed in the press conference that 50 pounds (22.6 kilograms) of Tannerite (used to make exploding targets for firearms practice and explosive devices) was found in Paddock’s car as well as 1,600 rounds of ammunition. Tannerite is used to make exploding targets for firearms practice and can also be used to make explosive devices.

The investigators are also pressing to find others apart from Paddock who may have been involved, Lombardo said, going against the police department’s earlier claim that the shooter was a lone wolf.

His speculation about the possibility that the shooter was aided came after an exchange in which he conceded investigators had not been able to identify any “person of interest” other than Marilou Danley, Paddock's girlfriend.

Authorities had questioned Danley, girlfriend after she returned to the U.S. from the Philippines Tuesday night.

Danley, in a statement Wednesday read by her attorney, Matthew Lombard, said she didn't know Paddock had planned to carry out a mass shooting. She described him as "kind" — and that he never gave any warning "that something horrible like this was going to happen."

"I loved him and hoped for a quiet future together with him," Danley's said in the statement. "He never said anything to me or took any that I was aware of that I understood in any way to be a warning..."

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