SICKLERVILLE, N.J. (CBS) — Police in South Jersey are asking for the public’s help in finding the cause of a head-on collision early Sunday evening that left four dead and two others seriously injured.

Gloucester Township Police Chief Harry Earle says it happened on Sicklerville Road between Dunlin Way and Mullen Drive just before 5 p.m. The sedans crashed head-on.

“A 2005 Toyota Camry. The driver of that vehicle, Richard Mason, age 53, is deceased, from Wilson Road in Winslow Township.”

Three people in the other car, a blue 2008 Camry, were also killed.

“Panagioti Ramoundos, age 43, Anastasia Ramoundos, age 80, Demetrious Ramoundos, age 77.”

Two other passengers, 59-year-old Jack Kalogridis and 74-year-old Betty Kalogridis are hospitalized in critical but stable condition.

At this point, Earle says investigators still don’t know how the accident happened, so they’re looking to the public for help.

“Any witness, anyone who believes they might have the slightest bit of information about this crash, we of course want to hear from them. They can call our tip line at 856-842-5560.”

The accident shut down Sicklerville Road for several hours.