A woman struck and killed by a car in Capitol Heights, Maryland, Friday night was riding her bike home, her family said. A witness who called for an ambulance said two cars appeared to be racing southbound when they passed the witness' car. A black or dark-colored Dodge Charger struck Clark and kept going, police believe. Donna Holliday Clark, 56, of Forestville, was a fitness enthusiast, but she wasn't out for exercise when she was struck about 11 p.m. on Ritchie Road. Clark was struck from behind, investigators said.