President Donald Trump on Monday called the mass shooting in Las Vegas "an act of pure evil," and said he would visit Las Vegas on Wednesday to meet with victims' families and first responders.

"We are praying for you and we are here for you," Trump said in a live statement from the White House Diplomatic Room. "We ask God to help see you through this very dark period."

The president struck a note of unity following the mass shooting in Las Vegas on Sunday night, which authorities say left at least 50 people dead and as many as 400 injured. It was the deadliest mass shooting in modern U.S. history.

"Our unity cannot be shattered by evil," Trump said. "Our bonds cannot be broken by violence. And though we feel such great anger at the senseless murder of our fellow citizens, it is our love that defines us today -- and always will, forever."

Trump also thanked first responders "for their courageous efforts and for helping to save the lives of so many.

"The speed with which they acted is miraculous, and prevented further loss of life. To have found the shooter so quickly, so soon after the first shots were fired ... shows what true professionalism is all about."

Police identified the suspect early Monday as 64-year-old Stephen Paddock, a Nevada resident who was found dead in his hotel room.

According to a statement from the Las Vegas Metropolitan Police Department, "Paddock opened fire on a crowd of more than 22,000 concert-goers from his hotel room on the 32nd floor of the Mandalay Bay Hotel on Sunday evening at approximately 10:08 p.m. The victims were across the street attending the Route 91 Harvest Festival concert when bullets rang out."

Trump tweeted his condolences to the victims of the attack early on Monday morning.

Trump tweet.

The White House said the president is receiving regular briefings on the progress of the investigation. Police have yet to identify a motive for the killings.