Police found four explosive devices in the Wheaton residence of James J. Lee, the man killed after a lengthy hostage standoff at the Discovery building, and are searching for other bombs they fear he may have constructed.

Lee, 43, had four devices strapped to his back when he was killed by police in the lobby of the Silver Spring building Wednesday, authorities said. They have determined that those explosives would have probably been fatal to him and could have injured the three people he held hostage if they had detonated.