Masked gunman killed in shootout at Dallas courthouse

DALLAS -- An Army veteran wearing a mask and carrying more than 150 rounds of ammunition for his high-powered rifle was shot dead Monday after he opened fire outside a busy federal courthouse in downtown Dallas, authorities said.

Federal officers killed 22-year-old Brian Isaack Clyde after he approached an entrance of the Earle Cabell Federal Building and began shooting, shattering the glass panes in a revolving door.

"It's a lot of rounds -- a lot of rounds at his disposal, a large powerful weapon at his disposal," FBI agent Matthew DeSarno said.

Clyde's attack began about 8:40 a.m., and three officers from the Federal Protective Service who were stationed at the building confronted him. DeSarno and other officials praised their courage at a news conference.

Officials are still trying to determine a motive, but said there was nothing to indicate the presence of any other shooters or threats to the city, DeSarno said.

DeSarno said Clyde was discharged from the Army in 2017. He served as an infantryman from August 2015 to February 2017 and achieved the rank of private first class, according to the Army.