Jeff and Matthew Barger were headed toward Dubuque on Monday afternoon when they saw thick black smoke and flames rising into the sky ahead. As the father and son continued south on U.S. 35/61/151, they soon saw a semi-tractor trailer engulfed in smoke in the distance. They drove past the line of cars pulled over to the side of the road, worried there might still be someone in the truck. Two semis had collided on the highway north of Dickeyville shortly at about 4 p.m., and flames soon would engulf the vehicles. “I’m 59 years old, and I’ve never witnessed that before in my life,” said Jeff Barger, a professional photographer from West Bend.