An 18-wheeler completely burned after catching fire on the expressway in Edinburg when a mattress flew off a vehicle Tuesday morning, according to Edinburg police. 

Preliminary investigation reveals a pickup truck was traveling northbound on 281 when a mattress flew off and went under the 18-wheeler traveling behind it. 

The mattress caught on fire first, causing the 18-wheeler to catch on fire, according to Lt. Rey Sepulveda with the Edinburg Police Department. 

The 18-wheeler was completely burned. 

The driver of the 18-wheeler was able to get out in time and is fine, Sepulveda said. Police say the driver of the pickup truck left the scene.

Traffic has been reduced to one lane in the area as authorities work to clear the scene. 

Edinburg police continues to investigate the case. 

No charges are known at this time.