This is the dramatic moment police wrangled a knife-wielding customer rampaging in a bank in Thailand.

Officers rushed to the Siam Commercial Bank in Kalasin province to confront the crazed man threatening tellers with a blade on September 14 evening.

Footage shows the chaotic fight inside the bank, with the armoured cops whacking the tank top-wearing suspect with their batons as he stood behind the counters.

The customer retaliated by hurling office equipment at the law enforcers.

Cops managed to subdue the out-of-control customer, pinning him down with a metal pole then dragging him out of the bank's glass entrance as terrified shoppers watched.

Bank employees said the 'rambling and confusing' customer had been trying to withdraw some 30,000 THB (840 USD) from his mum's account.

He had brought along her ATM card, her ID card, and his own ID. But when tellers told him it was against bank regulations to take money out of someone else's account, he pulled out a knife from his pocket and pointed it at the staff.

The terrified employees ran out of the bank upon seeing the knife and called police for help. One of them said they hid and locked themselves in the bank's document storage room.

Meanwhile, the officers said that after arriving at the scene, they had initially tried to negotiate with the man. However, he allegedly charged at them and tried to lock them out of the bank, prompting them to use physical force.

The man, who has not been identified by authorities, has been taken to the police station to calm down. Investigators said they will also be questioning his relatives before taking legal action.