GRAPEVINE (CBSDFW.COM) – The driver of an 18-wheeler is dead Tuesday after his vehicle overturned on the ramp from northbound State Highway 121 to eastbound Interstate-635 in Grapevine. It happened shortly before 1:00 a.m. just north of DFW International Airport.

According to authorities, a preliminary investigation found that the driver lost control of the big rig while traveling along the ramp. Police are still trying to determine what caused this to happen. The 18-wheeler then flipped onto its side and struck a guard rail. No other vehicles were involved in the crash.

The driver was trapped inside of the big rig’s cab, though police said that he did not appear to be breathing. Crews had to stabilize the vehicle before he could be extricated. The man was finally removed at about 3:15 a.m. and pronounced dead at the scene. His name has not been released.

Firefighters from Grapevine and DFW International Airport got the big rig removed from the area and picked up debris that was scattered across the roadway, while officials from the Texas Department of Transportation assessed the damage that was done to the guard rail.

This kept the ramp closed for several hours early Tuesday morning, but it has since been opened back up to regular traffic.