BOSTON (Reuters) - Massachusetts' Hanscom Air Force Base operations returned to normal on Thursday after a routine test turned up trace evidence of explosives on a moving truck bringing a shipment onto the base, officials said.
No injuries were reported, no one was arrested and no one was suspected of any crime, officials said.
The Massachusetts State Police bomb squad and federal law enforcement officials spent several hours searching the large box truck, with a gate to the base closed and parts of the base evacuated as the search went on.
"Given the times we live in, we operate in an abundance of caution," Massachusetts State Police Major Fran Leahy told a news conference after the site was cleared. "What we're trying to figure out is how some trace explosive materials ended up on this truck."
Some shipping materials from the vehicle were taken to the State Police crime lab for further study, Leahy said. The truck was transporting the possessions of a base staffer who had recently moved into a new job, officials said.
About 10,000 people, including military staff and civilians, work at the 846-acre (342-hectare) site in Bedford, Massachusetts, which is about 15 miles (24 km) northwest of Boston and houses units overseeing acquisitions, cyber security and some nuclear operations.
Live aerial footage during the search showed a large truck with "Big Foot Moving & Storage" emblazoned on the side stopped near the base's gate with an armoured military vehicle parked nearby. Police said they had set up a 1,500-foot (457-meter) perimeter around the truck.
A person who answered the phone at the moving company and declined to give her name said that she was aware of the truck's presence at the base but had no details as to what was in it.
Reporting by Scott Malone; Editing by Gabriella Borter and Jonathan Oatis