Pilots of the doomed Asiana Flight 214 were flying too slowly as they approached San Francisco airport, experts said, and investigators believe rescue crews could have run over one of the two teenagers killed in the crash.

Police officers threw knives up to crew members inside the burning wreckage of Asiana Airlines Flight 214 so they could cut away passengers’ seat belts.

Several dozen people were injured when two US light-rail trains collided, authorities said.

An explosion shook buildings in central San Francisco today after a manhole cover exploded in the street.