Colne Community College school bus roof sliced open
7 December 2012 Last updated at 16:21 GMT
Pupils who were travelling on an Essex school bus when the top was sliced "like a can opener" by a tractor-mounted trimmer have been talking about their ordeal.
About 45 Colne Community College pupils were on the double-decker bus when it collided with the tractor in Wivenhoe, near Colchester, on Thursday.
Four children suffered cuts and bruises caused by glass and broken metal. Nobody needed hospital treatment.