The New South Wales Police Bomb Squad has been sent to Chatswood train station, on Sydney's north shore, after thieves tried to blow-up an automatic teller machine (ATM).
The attempted robbery is one of four targeting ATMs across Sydney overnight.
Police say the thieves tried to remove three ATMs at Penshurst, Milperra and Georges Hall between 2:00am and 4:00am (AEDT).
The machines and their surroundings sustained extensive damage.
At about 4:00am, a man saw a group trying to break-in to the ATM at Chatswood railway station.
He told police when he disturbed them, one of the four men threatened him with a handgun.
They drove away in a dark-coloured car.
It is believed the men used an acetylene gas to try and remove the machine from the wall, but were interrupted by the passer-by.
Police say all the machines belong to St George Bank.
They are still trying to work out if any money was stolen.
source: Three ATMs blown-up by Sydney thieves