FRANKLIN TOWNSHIP, N.J. (CBS) — Two people were killed and four were critically injured in an early morning crash on a heavily traveled road in South Jersey.

The fatal crash happened at 6:12 a.m. Tuesday in the northbound lanes of Route 55 near Route 40 in Franklin Township.

Investigators say a minivan lost control and struck a tree. State Police say a total of six people were in the van when it crashed.

The New Jersey State Police says one person was pronounced dead at the scene. Sources say a second person later died after being transported to an area hospital.

One of those killed has been identified as Norma Santiago, 47. The driver, who police say was the only one wearing a seatbelt at the time of the crash, was also killed, but police are not releasing his/her identity until the family has been notified.

A total of four others were air-lifted to an area hospital, where they are in critical condition.

At one point, both sides of Route 55 were shutdown so medical helicopters could land at the scene.

The cause of the crash remains under investigation.

Top Content On CBSPhilly

Watch & Listen LIVE