A weekend traffic crash involving a fuel tanker near Loveland that spilled upward of 11,500 gallons of diesel fuel is thought to have been caused by a drowsy driver, the Colorado State Patrol said Monday.

Interstate 25 between exits 255 and 257 was shut down in both directions for more than 36 hours, from about 1 a.m. Saturday until Sunday afternoon after the fuel tanker, which was going northbound, rolled and burst into flames, spilling tens of thousands of gallons of fuel, the CSP said.

The driver, 67-year old John Brothersen of Henderson, was pulled from the wreckage with only moderate injuries and taken to a hospital. Troopers said he was driving while tired.

The area of the crash is under construction with a reconfiguration of traffic.

Sign boards and a regulated reduced speed were in effect.

Troopers said drugs and alcohol, excessive speed, overweight and mechanical defect are not suspected as contributing factors.

The crash remains under investigation.

Bothersen was issued a citation for careless driving, troopers said. No other vehicles were involved in the crash.

The CSP warned that drivers experiencing yawning, frequent blinking and drifting between lanes to pull over and rest.