The fire started after thieves attempted to remove an ATM machine from the Mega Petroleum Filling Station in Whitchurch High Street just after midnight.
The only description of the thieves at this time is that they were 'three men' - they were unsuccessful with the attempt in Whitchurch but did manage to steal some cash after attempting the same thing at the Post Office in Mill Street, Eynsham near Witney, Oxfordshire, a couple of hours later.
Investigating officer Detective Sergeant Justin Harris said: “We believe that the same offenders are responsible for both these incidents and we would like to speak to anyone who witnessed either offence, or who has any information which they think could be relevant to our investigation.
“If you have any details which you think could help, please call the Thames Valley Police non-emergency number on 101, quoting reference numbers 43190037114 and 43190037160.”
Fire crews were called to the Mega Petroleum filling station, Whitchurch, following reports of smoke coming from the cashpoint and later identified the cause as 'a small fire in an external cash machine'.
Two fire crews from Aylesbury attended the scene and firefighters used a dry powder extinguisher, a thermal imaging camera and a toolkit to tackle the blaze.
The petrol station remained closed through the night and into the morning with a police presence remaining on site.
Whitchurch residents reported 'hearing a loud bang that sounded like a firework'.