WATCH: Brother Of Vegas Shooter Says He’s ‘Completely Dumbfounded’ [VIDEOS]

The brother of the man who killed at least 50 people at an outdoor music festival on the Las Vegas Strip says he’s “completely dumbfounded” by the shooting, which is the deadliest in modern U.S. history.

In a brief interview with the Orlando Sentinel, Eric Paddock says he can’t understand what happened. He also said he’s made a statement to police.

Country music star Jason Aldean was performing Sunday night at the end of the three-day Route 91 Harvest Festival when the gunman opened fire from inside the Mandalay Bay Hotel and Casino.

Authorities say 64-year-old Stephen Craig Paddock killed himself after the shooting. Police have not yet determined a motive.

Vegas Gunman’s Brother: “Find out where he got the machine guns from…” pic.twitter.com/T8YlhEtWN6

— Breaking911 (@Breaking911) October 2, 2017

Las Vegas police say more than 400 people were hospitalized in the mass shooting at a country music concert.

Police said Monday morning that the shooter, 64-year-old Stephen Craig Paddock was found dead in a hotel room with as many as 10 firearms.

NEW: Gunman’s brother says his brother’s partner, Marilou Danley, worked at one of the hotels in Las Vegas pic.twitter.com/ntkjqrCmJl

— Breaking911 (@Breaking911) October 2, 2017

Authorities say that 406 people were taken to hospitals and 50 of those are dead, including an off-duty Las Vegas police officer. His name was not immediately released.

Clark County Sheriff Joseph Lombardo says Paddock first checked into the Mandalay Bay casino-hotel on Sept. 28 and was found dead inside a hotel room.

Two on-duty officers were also hurt. One of those has been upgraded from critical to stable condition.