An Absa ATM in Ladysmith, northern KwaZulu-Natal, was blown up at the weekend - the second machine to be hit in the town.
Last week police shot and killed two would-be bombers and arrested members of an ATM bombing syndicate in Imbali, a Pietermaritzburg township.
Two suspects are under police guard in hospital and are expected to appear in court today.
Police spokesman Superintendent Muzi Mngomezulu said the ATM in the residential area was blown up, but the gang could not take the money.
"It appears the bombers did not have enough explosives or tools for the job," he said.
He urged the public to be vigilant when using ATMs.
"If people suspect anything, they should contact police immediately.
"They should not approach ATMs if they suspect something," he said.
Mngomezulu said police were investigating the connection between ATM and cash-in-transit robberies.
"Police are working very hard to complete this operation.
"We only hope that the community will always tip off police whenever they hear of such plans," he said.
Mngomezulu said the arrest of the two bombers was just "the tip of the iceberg".