A northbound car apparently flipped over the guardrail and into the southbound lanes, landing on another vehicle, just before 7 a.m.
Eyewitness News is told two people were taken to St. Luke's Hospital, one in critical condition.
Southbound lanes were temporarily closed south of West 125th Street, and southbound traffic was backed up to the George Washington Bridge.
Meanwhile, one lane was closed northbound for the police investigation.
However, traffic was back to normal just before 10 a.m. this morning.