Roseville police are investigating a traffic accident that killed a 27-year-old Citrus Heights man Tuesday. At 3:30 p.m. Sunday, Roseville police and fire responded to an accident in which a 1994 Nissan four-door sedan occupied by two people hit a tree on Hickory Street at Church Street, said Dee Dee Gunther, spokeswoman for the Roseville police, in a press release. The passenger, Joseph Carrel Cowles, was taken to Sutter Roseville Medical Center, where he died this morning from his injuries.