A gunman opened fire in the lobby of a Las Vegas federal building Monday morning, killing a security guard and wounding a U.S. marshal, according to local police. The shooting reportedly ended at about 8 a.m. when the gunman was shot and killed at a building across from the initial scene in downtown Las Vegas, one FBI agent said. Though the shooter’s identity has not been revealed, a spokeswoman for the city’s police department said, “It looks like he went in there and just started unloading.” The multi-story building, which police and federal agents swarmed this morning, is the home of the federal courts and offices for federal officials, including U.S. Senators Harry Reid and John Ensign. Police are reportedly currently searching the building floor-by-floor.