The South Dakota Highway Patrol is investigating a morning crash that killed four people in Spink County Wednesday.
It happened at the intersection of U.S. Highway 281 and South Dakota Highway 20 near Mellette.
Investigators say 71-year-old Wesley Allen Frasard of St. Clair Shores, Michigan was driving a Ford Excursion with four other Michigan men inside and didn't stop at a stop sign. That's when the SUV hit a semi.
Frasard and three other men in the vehicle died. Fifty-two-year-old Thomas Edward Thorngate of St. Clair Shores, Michigan, suffered life-threatening injuries.
The accident happened shortly after 5:30 Wednesday morning.
"I was getting ready for work and I heard a loud boom noise, which we have trains loading all the time, so at first I thought it was a train," Zina Shepherd said.
But Shepherd came upon the accident scene on her way to work instead. She works at a gas station near the crash and said numerous emergency vehicles responded quickly, including the CareFlight helicopter.
Law enforcement says 50-year-old Doug Elmer Carnahan of Bottineau, North Dakota, was driving the semi. He suffered minor injuries.
Clean-up following the accident continued for hours.
"When you're involving a semi tractor and trailer, a large debris field and the severity of the crash, usually it can take four, five, six hours, up to all day," Lieutenant Doug Coughlin with the South Dakota Highway Patrol said.
The crash ruptured a diesel tank on the semi. The Spink County emergency manager determined local firefighters cleaned the spill properly.
Coughlin says a crash like this one could take weeks to fully investigate. Specialists spent hours mapping the scene Wednesday.
From the neighboring gas station, Shepherd's heart goes out to families involved and hopes something like this doesn't happen again.
"Just make sure everybody drives safe," Shepherd said.
Law enforcement kept traffic on Highway 281 moving but officers diverted south-bound vehicles a mile east through Mellette.
The other passengers who died in the accident were 68-year-old Ledger John Frasard Jr., 77-year-old William Edward Petrocy, both of St. Clair Shores, and 69-year-old Nikolaos Andreopoulos of New Baltimore, Michigan.