Masked gunman killed in shootout at Dallas courthouse

This undated photo provided by Del Mar College in Corpus Christi, Texas, shows Brian Isaack Clyde. Clyde, an Army veteran wearing a mask and carrying more than 150 rounds of ammunition for his high-powered rifle, opened fire outside a federal courthouse Monday, June 17, 2019, in downtown Dallas. Clyde was then shot dead in a shootout with federal officers. (Courtesy of Del Mar College via AP)
Federal employees take cover behind a car in a parking lot as shots are fired Monday morning, June 17, 2019 at the Earle Cabell federal courthouse in Dallas. A masked gunman opened fire Monday on a federal courthouse in Dallas before being fatally shot in an exchange of gunfire with federal officers, witnesses and authorities said. No officers or citizens were injured. (Tom Fox/The Dallas Morning News via AP)
Security officers, left, and a member of the U.S. Marshal's Service, right, head towards the downed shooter after shots were fired Monday morning, June 17, 2019 at the Earle Cabell federal courthouse in Dallas. A masked gunman opened fire Monday at the Earle Cabell federal courthouse before being fatally shot in an exchange of gunfire with federal officers, witnesses and authorities said. No officers or citizens were injured. (Tom Fox/The Dallas Morning News via AP)

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.