The Penobscot Narrows Bridge is back open again after a bomb threat at Fort Knox in Prospect closed the bridge for more than two hours.Officials say park staff found a threatening note just after noon. There’s no word on exactly what that note said.The Waldo County Sheriff’s Office was assisted by State Police in the investigation. Local police and fire were called in to direct traffic while the bridge was closed.Everyone in the park was asked to leave while officials searched the area. State Police brought in bomb sniffing dogs, too.Officials say nothing was found during that search.Waldo County Sheriff, Scott Story, says cooperation helped with the investigation. “There are plans in place to deal with these sorts of things, people all know their jobs when they get here. They know how to deal with traffic. The park staff here again they know what to do, that makes thing go a lot quicker, a lot easier.””Memorial day is a big weekend and the law enforcement folks responded very well so I hope they can get this under control, get going, we have a great weekend.” adds Leon Seymour, Executive Director of Friends of Fort Knox.Officials are looking for someone they say was seen running from the park restrooms to Route 174 around the time the note was found. They describe him as being in his late teens or early twenties, 5’8″ to 5’10”, slender, with light brown or redish hair. They say he was wearing a dark blue tee shirt and black jeans.If you have any information that could help them in their investigation, You’re asked to call the waldo county sheriff’s office at 338-2040.