Squad 33 (4) and Traffic 33 responded this morning at 04:57 to I81 NB MM53 for an unknown injury accident. Chief 7 arrived with one vehicle off the roadway and a tractor trailer involved. Crews assisted with patient care and checking for fluids. It was determined that the passenger car had crossed the median from SB to NB into the path of the tractor trailer. Crews were on scene over an hour. Company 33 was assisted by R45, Sq31, and Traffic 31.