Two years after a madman set up a sniper's nest inside a Las Vegas highrise hotel room, lawyers representing some of the hundreds wounded and family members of the 58 killed announced Thursday they've reached a deal with MGM Resorts that could pay them up to $800 million -- but while the money may be settled, the motive for the massacre remains unknown.

The announcement comes as events this week marked the two-year anniversary of the attack, in which gunman Stephen Paddock opened fire on concertgoers outside the Mandalay Bay resort on Oct. 1, 2017. Las Vegas law firm Eglet Adams says the amount of the settlement depends on the number of plaintiffs who choose to take part.

"While nothing will be able to bring back the lives lost or undo the horrors so many suffered on that day, this settlement will provide fair compensation for thousands of victims and their families," Robert Eglet, a lead Plaintiffs' Counsel, said in a statement. "MGM Resorts is a valued member of the Las Vegas community and this settlement represents good corporate citizenship on their part.

He added: "We believe that the terms of this settlement represent the best outcome for our clients and will provide the greatest good for those impacted by these events."

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MGM, which owns the venue where the attack was carried out, has been defending itself from hundreds of liability lawsuits.

"Our goal has always been to resolve these matters so our community and the victims and their families can move forward in the healing process. This agreement with the Plaintiffs' Counsel is a major step, and one that we hoped for a long time would be possible," Jim Murren, the Chairman and CEO of MGM Resorts, said in a statement. "We have always believed that prolonged litigation around these matters is in no one's best interest. It is our sincere hope that this agreement means that scenario will be avoided."

The law firm says an independent party will be appointed by a court to evaluate claims and dole out money from the settlement fund, and that the entire process should be completed by late 2020.

"The settlement fund will be funded by MGM Resorts' insurers with a minimum of $735 million," the Eglet Adams law firm says. "Depending on claimant participation, MGM Resorts will add additional amounts, up to $800 million."

Paige Gasper, a college student who was left with shattered ribs and a lacerated liver after being shot in the Las Vegas massacre, said Thursday her "hope is that our pain and the continuing daily struggle we face will not be forgotten and that we continue to honor the 58 people we lost that night."

She added that she hopes "this settlement sends a message to large companies like MGM to do more to protect people and prevent horrific events like October 1st."

Gasper is being represented by The Simpson Tuegel Law Firm in Dallas, which says its clients are among those who have reached the settlement with MGM.

The motive for the shooting -- which was the deadliest in modern U.S. history -- is still unknown.

The FBI’s agents and behavior specialists spent more than a year investigating the attack, but could not reach a conclusion.

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Aaron Rouse, the special agent in charge of the FBI’s Las Vegas office, said in January that Paddock acted alone when he planned and carried out the attack. The 64-year-old fatally shot himself as police arrived into his hotel suite.

Las Vegas police also closed their investigation in August 2018 without establishing a motive.

Paddock, who was a retired postal service worker, accountant and real estate investor, owned rental properties and homes in Reno and in a retirement community more than hour’s drive from Las Vegas. He also held a pilot’s license and liked to gamble tens of thousands of dollars at a time.

Police characterized him as a loner who had no religious or political affiliations, despite reports he had ranted about the Federal Emergency Management Agency “camps” set up after Hurricane Katrina and deadly standoffs between law enforcement officers and militia groups at Waco, Texas, in 1993 and Ruby Ridge, Idaho, in 1992.

Authorities said he began to stockpile weapons about a year before the attack and spent $1.5 million in the two years before Oct. 1, 2017. He also started to distance himself from his girlfriend and family.

Paddock sent his girlfriend, Marilou Danley, to visit her family in the Philippines two weeks before the attack. He also wired her $150,000 while she was there. She returned to the U.S. after the shooting and told authorities he had complained that he was sick and doctors told him he was suffering from an incurable “chemical imbalance.”

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In the days before Paddock fired more than 1,000 rounds with assault-style rifles into a country music festival, video footage showed him wheeling bag after bag into his hotel suite while security guards helped him. More than 30 video clips have been released showing Paddock interacting with Mandalay Bay staff, playing the casino’s gaming machines and transporting the bags.

Despite police finding 23 weapons in Paddock’s room after the shooting, he left no note to explain the chaotic mess he left behind.

The Associated Press contributed to this report.