A mid-sized jet that tried to land at a South Carolina airport ran off the runway and split in two Thursday, killing the two pilots on board and injuring two passengers.

The reason for the crash at the Greenville Downtown Airport was unclear. Witnesses say the plane appeared to land without a problem until it overshot the runway and went down a steep embankment.

The pilots’ names won’t be released until the Greenville County Coroner’s Office notifies relatives, The Greenville News reported . One pilot died at the scene; the other at Greenville Memorial Hospital. The two passengers, a married man and woman, are in critical condition at an area hospital.

The jet was likely landing to pick up more passengers when it ran off a runway embankment and hit nose first, said Joe Frasher, the airport’s director.

“We all saw it land, and for some reason it did not stop,” Frasher said.

Frasher said the crash, involving a Dassault Falcon 50 model, is the worst in at least 20 years at the airport.

(AP)