A West Midlands ambulance was attacked by vandals while a patient was being treated inside.
The damaged vehicle had to be taken off the road and could no longer be used by paramedics.
The incident happened in Woodside, Telford at about 1.20am on Monday morning.
The attacker smashed a wing mirror and threw mud on the windows.
West Midlands Ambulance Service are appealing for information which may help them identify the culprit.
Edd Davis, who works as an operations manager for West Midlands Ambulance Service in Shrewsbury, tweeted pictures of the defaced vehicle.
He said that it is not an unusual occurrence.