A Sparks Fire hazardous materials response team was called to investigate as an unknown fluid flowing from an overturned tractor-trailer early Tuesday. A section of Sparks Boulevard and an eastbound Interstate 80 freeway on-ramp were closed as a precaution during the investigation. Eastbound freeway traffic was backed up as NHP troopers briefly closed one lane.

Alcohol, drugs and excessive speed did not appear to be involved and the driver, Richard Wisner, 50, was unhurt, Nevada Highway Patrol Sgt. Jeff Figueiredo said at the scene. The substance, leaking from the overturned middle section of a triple tractor-trailer, flowed down and off the on-ramp but did not reach the freeway.

The Washoe County Health Department and the city of Sparks Environmental Safety Team were called to assist the Sparks Fire Department with the investigation. Precautions were taken because the unknown substance was considered a possible threat to public health and the environment, Figueiredo said. Unknown chemicals can be toxic, flammable and/or explosive and can flow through storm drains into the Truckee River.

Wearing protective gear, Sparks firefighters sampled the substance then used absorbent material to help contain the spill. H2O, a hazarous waste clean-up company, was later called in to complete the clean-up.

A Nevada Highway Patrol press release later revealed substances in the trailer as corrosive bromine salt, flammable methyl ethel ketone and liquid adhesives.

Figueiredo said it was unusual for only the middle section of a triple trailer to overturn. Other troopers speculated the trailer's load may have shifted as the truck was turning onto the freeway. No charges had yet been filed, according to the press release.