(Portland, OR) -- Crime Stoppers is offering a reward of up to one-thousand dollars for information leading to an arrest in the case of a bomb found near a Portland park. The explosive device had a tripwire attached, and was found on a trail near Forest Park last Saturday. Police describe the device as an improvised firearm with a pipe loaded with a shotgun shell, connected to a tripwire across the trail. The bomb, which was already inoperable, was safely removed by a bomb squad.