Police responded to a U.S. Immigration and Customs Enforcement office shortly before 7 a.m. Wednesday at 8101 North Stemmons Freeway in Dallas, off Interstate 35E. Sources told WFAA that police were searching for a possible sniper or multiple shooters. It remains unclear if there were any other shooters involved in the incident. Sources confirmed that one shooter was found dead on the roof of a nearby immigration attorney’s office.