Witnesses and British emergency services say a truck has struck an overpass and collapsed a pedestrian bridge onto one of England's busiest highways, injuring one person.

Witnesses say a truck hauling construction vehicles appeared to clip the bridge Saturday on the London-bound M20 highway 30 miles (48 kilometers) southeast of the British capital.

Ambulance officials say the injured man was a motorcyclist who came off his bike as the bridge started to collapse in front of him, but his injuries were not life-threatening.

The M20, one of two motorways that link London with the cross-Channel port of Dover and the nearby Eurotunnel terminal, was closed in both directions. The shutdown caused massive traffic jams on what was already an exceptionally busy three-day weekend for vacationers heading to and from France.