Bus driver injured in blast outside Washington state schools SEATTLE (Reuters) - A small chemical bomb exploded in a parking lot on the campus of two Washington state elementary schools on Monday, injuring a bus driver, law enforcement and school officials said. Officers swept the schools near Redmond, east of Seattle, but did not find any more explosives, a spokeswoman for the King County sheriff's office said. The schools were closed and a nearby middle school was temporarily placed in lockdown. The device was contained in a two-liter plastic soda bottle left in the parking lot and was made of a "low-level acid," similar to a household cleaner, the sheriff's office said. "It wasn't a sophisticated device," a spokeswoman said. A bus driver walking past the bottle bomb when it detonated sustained minor injuries and was being treated for exposure to fumes, according to a statement from Dr. Traci Pierce, superintendent of the Lake Washington School District. No students were injured nor were any nearby when the blast occurred in the parking lot of the two schools - the Emily Dickinson Elementary School and the Explorer Community School, Pierce said. Reporting by Victoria Cavaliere; Editing by Cynthia Johnston, Eric Beech and Jim Loney