A thief broke into an ambulance and stole paramedics' belongings as they treated a patient in a nearby house.
The crew returned to the locked vehicle in Northfield, Birmingham, to find the driver's window smashed.
CCTV footage from an on-board camera shows a man approach, damaging the vehicle before hoisting himself in.
West Midlands Ambulance Service (WMAS) said the "despicable crime" meant the ambulance could not be used for 999 calls.
Video of the break-in, which happened on Frankley Beeches Road at about 21:00 GMT on Sunday, shows a figure entering the courtyard where the vehicle was parked.
He approaches the door, and spends a few seconds attempting to gain entry to the vehicle.
At the end of the clip, he lifts himself up, and leans into the window before fleeing the scene.
The thief took a number of personal items, including an iPhone.
Nathan Hudson, from WMAS, said: "I cannot begin to understand why someone would do this to an emergency blue-lighted vehicle which has the sole responsibility of helping people.
"It really does make you question the morals of some people.
"It is unacceptable that ambulance staff, who are there to help people in their hour of need, are made to suffer by members of the public."
The out-of-service ambulance is being repaired.