A BOMB which ripped apart a Quedgeley cash machine was a 'makeshift' device.
Investigations are continuing into a midnight attack on HSBC at Olympus Park, in which thieves got away with up to £100,000 on April 8.
But police say the explosion was sparked by a 'makeshift device', although they refused to say what materials were used or whether they thought professional thieves were behind it.
A roaming gang could be travelling around the country to carry out the raids. Similar explosions have been carried out in Hampshire and Bristol in the weeks running up to the Quedgeley attack.
Police confirmed yesterday that they are still talking to other forces around the country to see if the explosions are connected.
A spokesman said: "We are continuing to look at if it is linked to incidents elsewhere in the country, although this has not yet been established."
But they also added: "There have been no arrests yet."
It emerged yesterday that CCTV footage inside the bank has not captured the faces of the thieves and is not being released to police, although officers have watched the images as part of their investigation.
People who have witnessed similar cash machine explosions have described them as sounding 'like a Second World War bomb' going off.
Other attacks have been more dangerous, with explosions taking place on petrol station forecourts near highly flammable materials.
But the Quedgeley raid saw thieves smash their way in through the front doors of the branch before blowing up the machine inside.
They then stuffed cash into a plastic bag before getting away.
A forensic officer said that the cash machine had been 'obliterated' by the blast.
Police are still appealing for help. Anyone with information is asked to contact them on 101 with crime number 478 of April 8.
