Updated at 7:00 p.m.
The Third Street tunnel has reopened following a nine-car pile-up that closed the northbound lanes for nearly three hours. Officials said that northbound I-395 remains backed up for about a mile and a half.
The crash occurred just before 4 p.m. in the northbound lanes of the Third Street tunnel near Massachusetts Avenue in the District, police spokesman Hugh Carew said.
Three people were hospitalized with injuries that were not life-threatening. The accident involved a dump truck and several cars in an apparent chain reaction.