A mass shooting targeting concertgoers in Las Vegas who were gathered for the last night of a popular country music festival has left at least 50 people dead and more than 400 injured.

Thousands of people had converged for the last night of the Route 91 Harvest Music Festival in an outdoor area known as Las Vegas Village, across the strip from the Mandalay Bay and the Luxor hotels. Country singer Jason Aldean was performing when the gunman opened fire, sparking a mad scramble for shelter.

(David Becker/Getty Images)

(David Becker/Getty Images) (David Becker/Getty Images)

Police have identified the gunman as 64-year-old Stephen Paddock, who died in a hotel on the Vegas stripe. THe gunman’s motive is unknown.

(David Becker/Getty Images)

(John Locher/Associated Press)

Police shut down the usually busy Las Vegas Boulevard, and authorities across the state and federal ranks converged onto the scene as dozens of ambulances ferried those struck by gunfire.

People were searched by police at the Tropicana Las Vegas as the shooting was happening.

(Chase Stevens/Las Vegas Review-Journal/Associated Press)

The killings at the sold-out festival mark the deadliest mass shooting in modern U.S. history. The previous was was in Orlando, where 49 people were killed when a gunman opened fire at the Pulse nightclub in June 2016.

(David Becker/Getty Images)

A nearby interstate was briefly closed, as was the international airport, while many hotels were put on lock down Sunday.

(John Locher/Associated Press)

In a tweet Monday, Trump offered “My warmest condolences and sympathies to the victims and families of the terrible Las Vegas shooting. God bless you!”

White House spokesperson Sarah Huckabee Sanders said Trump was “briefed on the horrific tragedy in Las Vegas.”