Four people died in a major traffic wreck immediately west of where Interstate 90 crosses Minnesota Highway 13 shortly after 2:30 p.m. Wednesday.

Traffic had been restricted to two lanes on the westbound side of I-90 because of construction on the eastbound lanes.

According to witnesses who were driving other vehicles and the Minnesota State Patrol, a woman driving an eastbound 1996 Toyota Corolla swerved in front of a westbound semi. The driver of that semi, Randy Pedersen of Swaledale, Iowa, said the crash damaged his steering, causing his semi to cross into the oncoming traffic.

The truck hit a 1996 Honda Odyssey minivan head-on. The semi continued through the muddy ditch and onto the new and unused pavement of eastbound I-90, where it stopped.

All three passengers of the Honda died. The woman driving the Toyota also died.

Pedersen said he couldn’t understand why a driver would steer right in front of his truck, but a witness who had been in a Dodge Ram pickup just behind the Honda speculated the Toyota driver might have suffered a medical occurrence. To be sure, it could be any number of reasons: slick roadway, auto malfunction, fatigue.

The Toyota and the minivan were totaled. Pedersen, 56, was unharmed. The front of the semi was severely damaged. His load on a flatbed trailer was not damaged.

The names and ages of the deceased are expected to be released later today. A reconstruction team was called to the site to piece together how the crash took place.