A student brought to Kiona-Benton City High School on Monday a piece of metal pipe that apparently had been used to hold a lit firecracker, prompting officials to call the bomb squad.
The school was not evacuated Monday morning, and Benton County sheriff's deputies reportedly said there was no danger to the building at any time, school officials said.
As a precaution, officials called sheriff's deputies and the Richland police bomb squad to inspect the small piece of aluminum.
Authorities found no danger based on the inspection and their interviews with the student, who reportedly said he had exploded the piece of pipe at home.
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A message about the incident was read in classes to students and staff, officials said.
Benton County sheriff's deputies and bomb squad technicians also reportedly searched the student's home.