A St John Ambulance crew in Surrey had a tree blown on top of their vehicle while they had a patient on board.
Ray Pennock was treating his son-in-law's sprained ankle at Esher Rugby Club when winds caused the poplar to fall on the ambulance on Sunday.
The tree badly damaged the roof and back doors of the vehicle but the four people inside were unhurt.
Mr Pennock said: "You've never seen four St John people get out of an ambulance so quickly in your life."
He added: "The ambulance is possibly a write off. The back doors are all gone and the roof is stoved in.
"Ironically he [the man being treated] is my son-in-law and he's a paramedic in the ambulance service and he sprained his ankle while teaching kids rugby."