An early morning explosion on a Metrorail maintenance train injured one person, scattered debris an eighth of a mile and forced the closure for several hours of Interstate 66 east of Falls Church.

Shortly after 5 a.m., an eastbound engine and a flatbed car had just passed the East Falls Church Metro station when tanks of acetylene aboard the flatbed exploded, said Metro spokeswoman Mary Bucklew.

The Arlington County Fire Department extinguished the ensuing fire, which was fueled by hydraulic fluid and diesel fuel, about 6:10 a.m., according to Lt. Stevan Hynson. Fire investigators found debris from the explosion an eighth of a mile behind the train on the Lee Highway overpass. The operator of the train, Thomas Hoole, 29, of Waldorf, suffered cuts and bruises when he leapt from the train, Hynson said. A second crew member was not injured.

The explosion occurred on the section of track that is on the median of I-66. The Virginia State Police closed in both directions of the highway from 5:20 to 7:20 a.m., when firefighters determined that there was no danger of further explosions.

Fire Department investigators found a large piece of the engine's drive shaft 200 yards behind the train and believe it ripped off several hydraulic hoses when it fell from the train, Hynson said. The hydraulic liquid caught fire, heating up the acetylene, which then exploded. Another train hauled away the damaged equipment.

The accident had "virtually no effect on Metrorail service," which does not begin until 8 a.m. on Saturdays, Bucklew said. All Orange Line trains used the westbound tracks between Ballston and East Falls Church until the other side reopened at 9:30 a.m., she said.