A mother and her teenage son were killed early Monday morning after their car crashed into the back of a tractor-trailer on Interstate 495 in southern Prince George’s County, authorities said.

State police said 39-year-old Toykia Kenya Keys, 39, of Fort Washington, was headed north on the outer loop of I-495 near state route 414 when she drove into the back of a tractor-trailer going the same way. Keys and her 14-year-old son, Kamany Love, were pronounced dead at the scene of the crash, which occurred just before 1 a.m., authorities said.

The driver of the tractor-trailer, a 44-year-old Baltimore man, was unhurt, police said.

A witness told investigators that Keys appeared to be speeding and driving aggressively before the crash, state police said. They said detectives are still working to determine her exact speed and other factors that might have contributed to the incident.