Police suspect small blasts that hurt woman in a portable toilet, damaged mailbox were pranks

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Authorities were searching Monday for a person whose homemade explosive device went off inside a portable toilet during a softball tournament, injuring a woman in what was likely a prank.

Kari Finch, 40, of Spokane, Washington, suffered minor injuries when the device went off on Saturday at the International School of Beaverton in Aloha, a Portland suburb.

She was treated for an injury on the back of her head and chemical burns, said Sgt. Bob Ray of the Washington County Sheriff's Office.

Whoever set off the device might have thought it was "cool or funny at the time.," Ray said, adding "it's anything but that."

He said the woman could have been blinded if chemicals had gotten into her eyes.

A similar device was set off in a nearby mailbox on Friday night. A few minutes after the Saturday blast inside the portable toilet, a third device went off in a mailbox about a quarter-mile south of the school.

Investigators believe all three incidents were related and the devices likely consisted of materials available at grocery stores.

The blasts could result in felony charges related to making and possessing explosives as well as assault, Ray said. "It's very serious," he said.

The woman gave a physical description of a teenage boy who left the toilet just before the explosion, but Ray said it's unclear whether he was involved in planting the device.

The sheriff's office was not releasing the description but was working to identify the teen.

Deputies evacuated the area where about 200 people were gathered for a softball invitational. They also contacted the Portland police bomb squad, which assisted with a search for additional devices at the school and adjacent park.

Games scheduled to be played at the site were moved, said Kimberley Wilson, assistant director of the Valley Invitational Tournament, which featured more than 200 teams from 10 states and Canada at two-dozen sites in Washington and Clackamas counties.

"It was more of a precaution," Wilson said. "Parents were too traumatized and that's not the goal of this tournament. We were deeply devastated by what happened."