Authorities say a man drove a pickup truck onto the grass at the National Mall and said he thought he was exposed to anthrax.

U.S. Park Police tell NBC4-TV that the man drove onto the mall Tuesday afternoon in front of the Capitol, near the reflecting pool, where officers could be seen wearing gas masks and talking with a man wrapped in a blanket, and a robot appeared to be checking the truck.

Authorities closed several streets in the area, and emergency responders were told to suit up, but firefighters quickly determined there was no hazardous material, fire department spokesman Doug Buchanan said.