PHILADELPHIA — All lanes are open nearly four hours after a tractor-trailer struck a fire truck, injuring five firefighters and the truck driver and bringing traffic to a halt on heavily traveled Interstate 95 in Philadelphia.

Authorities say the injuries are not life-threatening.

The jackknifed tractor-trailer blocked the southbound lanes causing some motorists to get out of their cars while others slept as they remained stuck on the highway for hours.

The crash occurred in the southbound lanes around 3 a.m. Thursday when the tractor-trailer driver lost control and hit the fire truck, which had responded to an earlier accident. The firefighters and the tractor-trailer’s driver have been taken to a hospital.

Police turned some vehicles around and diverted traffic to Interstate 676 before towing the truck and reopening all lanes.