GREENVILLE (WSPA) – Two people are dead and two others critically injured after a jet crashed at the Greenville Downtown Airport around 1:30 p.m. Thursday.

The deceased are the pilot and co-pilot.

The pilot has been identified as John Christian Caswell, 49, of Port Saint Lucie, FL. He died at the scene.

The co-pilot is 66-year-old Stephen George Fox of Indian Rocks, FL. Fox was pronounced dead at the hospital.

The two passengers aboard were a married couple. 

They were flying in a Falcon 50 12-passenger private jet that plummeted to the bottom of a bank, nose first at the end of a runway. 

“I was in the parking lot. I had just gotten back from lunch, and all of the sudden I heard this loud boom,” said Gina Romero, who works near the airport.

Officials do not yet know what went wrong.

“It was a normal landing is all I can tell you,” said Greenville Downtown Airport Director Joe Frasher. “We all saw it land. And for some reason, it did not stop. It ran off the end of the runway.”

After crashing into the fences on Airport Road, one of the jet’s engines continued to run. 

“It was a very high throttle setting with a lot of dust being very loud,” Frasher said. “I think one of the pilots was laying on the throttle and was unconscious, so it was very difficult to get in the aircraft.”

The noise of the engine caught the attention of people who work near the runway. Several people told 7 News they are used to hearing the planes for a few moments, but they knew something was wrong when the noise of the jet’s engine didn’t stop. 

“Everyday they fly above my job,” Romero said. “Everyday we see them in and out, so it was just very shocking because we hadn’t experienced this. It was the first day that we saw something like this happen.”

Firefighters broke a window to get into the plane. They then cut back the throttle and searched to cut off the fuel; however, some of it spilled.

“Incident commanders have soaked up most of the fuel that was leaking and damned up the ditches so that the fuel does not spread,” Frasher said. 

The Federal Aviation Administration secured the scene. The National Transportation Safety Board will arrive Friday morning to investigate. 

Frasher said the plane had a data recorder and a voice recorder onboard.

The jet crashed on Airport Road after going off the runway. Roads on the south side of the airport were blocked.

Airport Road is expected to remain closed for three days.