Marshalltown police found a pipe bomb Tuesday morning. The bomb was about five inches long, made of white plastic with a partly burned fuse in it. It was found in a yard on Marshalltown’s Fremont Street. The state fire marshal’s office removed the bomb, took it to the police department’s firing range to examine it, and used a high-pressure water spray to disarm the device, a standard procedure. That’s when it exploded. Police have no idea why someone put the bomb in that yard or who did it.