A Missouri truckstop was shut down last week and local residents evacuated for six hours because of a leak of a suspected hazardous material from a tractor-trailer’s cargo.

The leak was discovered about 5:30 p.m. last Thursday after the rig pulled into the parking lot of the TravelCenters of America truckstop just north of Interstate 70 in Concordia, MO, reports the Associated Press. The truckstop and two nearby fast-food restaurants were closed while a hazardous materials team investigated. About 25 homes north of the interstate were evacuated, but residents were allowed to go home at 11:30 p.m.
The substance turned out to be a sodium hydroxide based cleaning agent that leaked from a barrel in the trailer and reacted with the aluminum floor. Crews spread an absorbent material to clean up a small amount of the cleaner that leaked out of the trailer doors on to the parking lot. The rest of the cargo was transferred to another vehicle the next day.