An 8-year-old playing at school in Poway was treated by a campus nurse for finger burns after he picked up a ball of tin foil containing an explosive, a Sheriff’s Department spokeswoman said Wednesday.

The third-grader at Pomerado Elementary School found the disguised bomb at 11:30 a.m. Monday on the playground, spokeswoman Cathy Wilder said.

Similar booby traps--used by drug dealers to protect them from police raids--have been found around drug labs and in San Diego County schools, Sgt. Conrad Grayson said.

“People who have drug labs test their devices on school grounds because they’re usually empty at night,” Grayson said.


The chemical mixture is extremely sensitive to shock and detonates easily, he said.

“If the bomb is slightly disturbed, it goes off; it’s that sensitive,” he said.