A “hazardous substance problem” has closed Interstate 35 north of Dallas-Fort Worth near Valley View, Texas Department of Transportation officials said Friday morning.

Around 9:00 a.m. only one lane was open in both directions.

After a three-vehicle collision involving a rock hauler and a passenger vehicle carrying radioactive medical dye, a hazardous materials team was called in to inspect the area, according to Cooke County emergency management officials.

Officials said the outer packaging of one of the medical packages was opened, although the inner packaging was intact.

“Out of an abundance of caution, Hazmat was called in to evaluate the item,” according to a social media post from the district. “The item has been assessed and moved to a safe location.”

The crash occurred around 4 a.m. on the southbound side of I-35 near the Hockley Creek overpass and involved three semi-truck trailers and a passenger car. Authorities said one of the trucks caught fire and the driver died.

Diesel and automotive oil were still waiting to be removed Friday morning. The interstate remained congested in the area.

People planning to travel on the highway in the area north of Denton, about 20 miles south of the Oklahoma border in Cooke County, should prepare an emergency plan as crews work to clear the road, TxDOT officials say.