Four persons were killed and 40 others injured, 12 of them critically, when their van overturned at Mongalbari on NH 34 in Malda district on Wednesday.
The mishap took place when some residents of Pakuahat's Mallipara village were returning after a cremation, police said.
While one person died on the spot, three others succumbed to injuries in the hospital, they said.
The injured have been admitted to Malda Medical College Hospital, they said, adding the condition of 12 of the injured was critical.