Several attendees have reportedly tested positive.
Photos from the scene show complete destruction.
The crash happened around 7:45 p.m. Wednesday, Sept. 4.
Joseph Koopman died in a rollover crash in southwest Minnesota on May 17.
The crash happened Friday around 11:20 a.m. in Lyon County.
More than 8,000 gallons of diesel fuel escaped through a small hole in a pipeline.