Deno Yannarelli heard the boom of a truck crashing on Interstate 35W. Then a blast erupted from the truck that was already on fire. Suddenly the driver was engulfed in flames.

Yannarelli, working his sales job at the Roseville Chrysler Dodge Jeep Ram dealership Wednesday afternoon, jumped the fence near County Road C and ran to the driver.

“I grabbed him and threw him into the ditch,” extinguishing the flames, said Yannarelli, 58, of Minneapolis. “We were 10 feet from the truck and it blew and then it blew again.”

People on the other side of the fence screamed: “You’ve got to get out of there.”

With the help of another man, Yannarelli dragged the driver to the end of the fence line and lifted him onto the tailgate of a nearby truck. Yannarelli took off his shirt and laid it across the driver’s badly burned body, pouring water onto it that others nearby handed him.

“He was screaming,” Yannarelli said. All Yannarelli could do was hold the burned man, talking all the time during the 15-minute wait for the ambulance to arrive after being forced to navigate around the clogged roads. “I didn’t want him to go into shock,” he said.

The driver of this semitrailer truck lost control while southbound on Interstate 35W Wednesday afternoon. He was severely burned when the truck exploded as he ran back for a fire extinguisher when the truck exploded.

Lt. Tiffani Nielson, Minnesota State Patrol spokeswoman, said the driver was taken to Hennepin County Medical Center and is expected to survive.

Nielson said the driver was traveling south on I-35W about 2:30 p.m. when he lost control of the truck, swerved and hit the pole of an overhead road sign near County Road C. The truck was not carrying any cargo when it crashed, she said. It’s unknown what caused the driver to lose control.

Yannarelli said the driver got out of the truck immediately after the crash but was returning to the cab for a fire extinguisher when it erupted. “It must have blown four or five times,” he said.

The truck burned to the ground and nearby road signs melted, Yannarelli said.

Black smoke blocked the interstate, forcing the State Patrol to close both northbound and southbound lanes as the Wednesday afternoon commute began. The northbound lanes reopened about an hour later, but the southbound lanes remained closed for hours while inspectors determined whether the road sign extending over the road posed a hazard, Nielson said.

The afternoon commute was snarled while that portion of the interstate was closed and nearby roads were being used for detours.

Additional details about the accident and driver were not available.