Police were called to a disturbance at the Texaco garage on Moorland Villas, Yelverton, at just before 4am on Monday 7 September.
It is believed that three suspects were using gas cylinders to break into the cash point machine when it exploded and caught fire.
Fire crews from Yelverton, Crownhill and Tavistock arrived at the garage to find the fire had engulfed the cash machine at the front of the store.
Police officers in Tavistock are appealing for witnesses to the incident. A spokesman said: “We have spoken to the manager of the garage who has explained that the risk of further explosion is very low. The pumps are designed to be safe from fire incidents and the petrol is held in airtight containers set in concrete deep under the forecourt.
“However, the risk the suspects put themselves from an exploding gas canister is far higher.
“If you saw anything suspicious in the Yelverton area either before or after the explosion you can contact the police by email on email@example.com, or calling 101 quoting police log number 63 07/09/15.”