New Jersey State Police say two separate crashes involving jack-knifed tractor-trailers has left one person dead early this morning on I-287 northbound in Oakland.

The first crash occurred around 2:35 a.m., and the second around 2:49 a.m.

According to state police, in the area of milepost 58.2, a freightliner tractor semi-trailer struck another freightliner tractor semi-trailer in the rear in the area of milepost 58.2, causing the second tractor-trailer to overturn -- ejecting the driver. 

State police say the driver was transported to Hackensack Meridian, where he was pronounced dead.

State police say the second driver sustained non-life-threatening injuries.

I-287 was closed for around six hours. 

There were no other injuries. The causes of the crashes are unknown at this time.