Police in Ely saved the life of a man who was not breathing.
Officers received a GoodSAM alert for Chapel Street at 10.20pm on February 24.
On arriving, they found a man in his 30s who not breathing.
Officers carried out CPR and used a defibrillator and he began breathing on his own.
The man was then left in the care of the paramedics.
"We were able to hand over to the ambulance service who said the officers' actions were life-saving," said a spokesperson for Cambridgeshire Constabulary.
GoodSAM is an app that alerts people to suspected cardiac arrests occurring close to them.
This is done so they have the opportunity to assist before emergency services arrive.
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