Tumalo ‘boom’ source: Blown-up old fridge

Authorities checking reports of a loud “boom” near Tumalo Reservoir west of Bend Monday night found what it was Tuesday – and old refrigerator placed in an abandoned concrete pump house – then blown up with an explosive.

The explosion most likely resulted from use of a binary explosive called Tannerite, sold as an exploding substance for target practice, said Deschutes County sheriff’s Lt. Scott Shelton.

A sheriff’s office forest patrol deputy was dispatched around 7:45 a.m. Tuesday to check on the report of a blast from the area of Sizemore and Couch Market roads, Shelton said.

Residents living near Tumalo Reservoir Dam west of Bend said they heard the explosion about 7 p.m. Monday. It was believed to possibly be a sonic boom, so no one called 911 dispatchers at the time, Shelton said.

But residents said before the blast, about seven cars had been parked nearby, carrying about 20 people, all in cars apparently with out-of-state license plates.

An investigation found an older refrigerator had been placed in the old pump house and blown up, probably with Tannerite.

Shelton said, “This commercially sold product can be combined to create a significant explosion and can be extremely dangerous if used improperly.”

“Individuals involved in this type of activity could potentially face a number of criminal charges,” the lieutenant said in a news release.

Sheriff’s detectives and deputies will continue their investigation, Shelton said. Anyone with information was asked to contact the dispatch non-emergency number (541) 693-6911. You could also contact the Crime Stoppers Tip Line at 1-877-876-TIPS, or use the form on KTVZ.COM’s Crime Stoppers page. You can remain anonymous, and could be eligible for a cash reward.