What we know and don't know about Baltimore's Key Bridge collapse

A container ship rests against wreckage of the Francis Scott Key Bridge as night falls on Tuesday, as seen from Sparrows Point, Md. (Matt Rourke/AP)

Rescue efforts have turned to recovery in the tangled wreckage of the Francis Scott Key Bridge in Baltimore.

Authorities have recovered the bodies of two workers, and four others are presumed dead after a cargo ship struck the bridge early Tuesday morning, sending the structure — and anyone on it — plunging into the frigid Patapsco River.