Five people were killed Thursday in an accident that involved a car and a tow truck towing a box truck, officials said.

The accident happened shortly after 2:30 p.m. at Bake Oven and Mountain roads in Heidelberg Twp, Lehigh Co.

A car was traveling north on Bake Oven Road when it went through a stop sign and collided with a tow truck that was towing a box truck, said Pa. State Police.  After the crash, the two vehicles traveled off the road and landed on a grassy patch nearby.

Officials initially thought four people were killed in the crash, but the coroner confirmed late Thursday night that the total number of dead had risen to five. 

Three men and a woman in the car were killed, police said. Their identities were being withheld until their families could be notified.

The driver of the tow truck, Charles Oswald, 58, of Schnecksville, was also killed.

Walter Fries II, of Northampton, a passenger in the tow truck, was taken to Lehigh Valley Hospital near Allentown with moderate injuries, said police.

The car was not under the tow truck, as 69 News was initially informed, but it was extremely mangled, the coroner said.

Mountain Road was closed between Ulrich and Church roads; Bake Oven Road was closed at Fritzinger Road while police conducted their on-scene investigation, dispatchers said.

The accident remains under investigation by state police, officials said.

The National Transportation Safety Board (NTSB) was notified due to the high number of fatalities in the crash, according to police.