A major Baltimore bridge collapsed early Tuesday after it was hit by a large container ship.The missing people may have fallen into the water.The bridge carries Interstate 695 across the Patapsco River, southeast of the Baltimore metropolitan area.Wiedefeld said the incident is an active search and rescue mission and that vessel traffic into and out of the Port of Baltimore is suspended until further notice.This is a very large incident, it involves a very large footprint," Baltimore City Fire Department Chief James W. Wallace said in a press briefing. The National Transportation Safety Board launched a team to investigate the collapse, a spokesperson told CNBC.Sonar scans detected the presence of submerged vehicles, but could not disclose the number of cars involved, the fire department chief said. Asked if the ship was suffering any technical impairments, he said, "We do not have that information."Six people were missing after the collision at the Francis Scott Key Bridge, according to Paul Wiedefeld, Maryland's transportation secretary.The crash by the large container ship occurred around 1:30 a.m. ET,  when contractors were working on the bridge, according to Wiedefeld."We are going to make sure that this is not just not just rebuilt, but that we are going to rebuild in a way that remembers the people who this tragedy has impacted," Moore said."We haven't seen any credible evidence of a terrorist attack."