A school bus caught fire inside the Third Street Tunnel Monday morning while it was being towed, leaving the tunnel full of smoke.
About 40 to 50 cars were in the tunnel traveling on the northbound lanes at the time of the fire. Some people abandoned their cars to escape the tunnel. Police later escorted them back to their vehicles, News4's Darcy Spencer reported.
Police allowed northbound traffic to leave the tunnel via the southbound end of the tunnel. Otherwise, both sides of the tunnel were closed. Officials asked drivers to avoid the area.
Three police officers were hospitalized with smoke inhalation, Spencer reported. No other people were transported, but some were treated at the scene.
The fire appears to have been caused by a mechanical failure, Spencer reported. Witnesses said they heard an explosion.
The bus and tow truck belong to the military, Spencer reported.
Southbound lanes of the tunnel reopened to traffic about 12:45 p.m. All lanes had reopened by 3:15 p.m.
Stay with News4 and NBCWashington.com for more information.