A father and his 5-year-old son were killed, and a 3-year-old daughter was critically injured in a morning crash in South Jersey.

Shortly after 7 a.m., their Pontiac Grand Prix collided with a tractor-trailer carrying a load of paper products on Route 40 near Buck Road in Pittsgrove Township, Salem County, according to state police.

The father, 37, and his son died in the crash, and the daughter was flown by helicopter to Cooper University Hospital in Camden in critical condition.

The truck driver was not injured.

State police said this morning they had not identified the victims or determined the cause of the crash.

Route 40 was closed and traffic was detoured while police investigated.

Contact Michael Hinkelman at 215-854-2656 or hinkelm@phillynews.com or follow on Twitter @MHinkelman.