At least two people were killed and a stretch of a Wisconsin highway closed Wednesday following a fiery accident that left a semitruck on its head, officials said.

The semitruck was heading southbound on I-94 as it made a lane change and hit a construction barrier, then collided with a median barrier while trying to correct, Racine County Sheriff Christopher Schmaling said Wednesday. The truck burst into flames and some 911 callers reported explosions coming from the tractor-trailer.

Due to the force of the hit, the barrier moved into the northbound lane, causing three vehicles to crash.

A second semitruck in the northbound lane made an evasive maneuver into a ditch, went off the road and also burst into flames, Schmaling said.

“I can tell you in my 24 years on this job, this is the worst accident I've ever been a part of," Schmaling said.

The drivers of both semis are dead and two of the drivers in the northbound crash were transported to local hospitals wit serious injuries.

Schmaling said that authorities are investigating what cargo was being transported that might have caused the trucks to burst into flames.

Traffic in both directions on I-94 between Highway 20 and Highway G was shut for miles, according to a statement from the Racine County Sheriff's Department.

Racine County Medical Examiner Michael Payne confirmed that at least two people lost their lives in the horrific crash that happened about 11 a.m.

Pictures from the scene showed a burning truck that flipped, with its backside off the ground at a 45-degree angle.

John Drilling, a photojournalist for NBC affiliate WTMJ, was on the highway when the crash unfolded about 100 feet in front of him.

"I saw a semitrailer jump over the median," Drilling told his station. "It was traveling in the opposite direction, and it jumped over the median wall and hit the cars in front of me and a second later there was an explosion and everything caught on fire."

The deadly crash shook up the 30-year veteran Drilling.

"I slowed down as quickly as I could, but I was shocked," the photojournalist said. "It was just a shocking experience. It was horrible."

Southbound lanes of highway were reopened Wednesday night. But northbound lanes, which run toward Milwaukee, were expected to be closed overnight as crews repair pavement.

State transportation officials said they hope to have those lanes ready for traffic by the Thursday morning commute.