Police are investigating vehicle crashes that left a female driver and a teenage dirt-bike rider dead in separate accidents on Philadelphia streets.

The 50-year-old woman was killed after her 2004 GMC Envoy struck a tree on the 1300 block of East Washington Lane in East Germantown just before 7:45 a.m. Friday, Philadelphia police said.

She was pronounced dead at the scene at 7:56 a.m. No other injuries were reported. The circumstances of the crash remain under investigation.

Police on Friday also identified the 18-year-old dirt-bike rider who died in a Thursday afternoon crash in North Philadelphia.

Jose Colon of the city's Feltonville section was killed when he tried to pass a box truck, lost control, and crashed, officials said.

The 31-year-old male truck driver was turning onto Erie Avenue from Whitaker Avenue when Colon tried to pass him on his 2001 Yamaha.

He tried to squeeze between the truck and parked vehicles, bounced off the parked cars and got caught under the truck's rear tires, police said. Colon was taken to Temple University Hospital, where he was pronounced dead at 3:40 p.m.