An hour long-closure on the expressway in Mercedes to clean up a diesel spill was caused by a driver asleep at the wheel, according to the Mercedes Police Department.

The driver was hospitalized following the spill, Mercedes police investigator Leroy Hernandez said.

According to Hernandez, the driver of a blue Honda passenger car fell asleep at the wheel and collided with a truck Wednesday shortly before 8 a.m. on East Expressway 83 and Dawson Road.

“As a result of the impact, a diesel spill occurred from one of the vehicles,” Hernandez said. “Additionally, a total of six secondary crashes followed in a chain-reaction manner, further contributing to highway congestion and significant delays in the area.”

Crews were able to clean up the spill and the main lanes have since reopened.

The condition of the hospitalized driver was not immediately available.