Police looking for motive after man opens fire in workplace and kills two coworkers

Police are searching for a motive after a man shot three co-workers during an altercation at a northern Virginia business on Wednesday, before taking his own life along an interstate highway amid a police standoff. Marvin Grant, 37, opened fire at an equipment rental business, killing two co-workers and leaving a third hospitalized, Manassas Police Chief Doug Keen said at a news conference.Grant fled in a vehicle, but detectives were able to track his phone to the Harrisonburg area, Keen said. Keen identified the two workers who died as Richard Lamont, 48, and Christopher Serrano, 33. Workplace Shooting Virginia (WJLA)A third worker was in stable condition at a hospital in Fairfax, the chief said.Manassas is about 30 miles (50 kilometers) southwest of Washington, D.C.Grant later pulled over on I-81 in Augusta County and fatally shot himself during a standoff with Virginia State Police. A state police statement said troopers did not use force.The motive behind the shooting remains unclear, according to Keen.