BANGKOK (THE NATION/ASIA NEWS NETWORK) - "I'm sorry, I have financial problems" - that's what a lone gunman told a teller of a Thanachart Bank on Rama III Road on Thursday (Sept 7) before escaping with 270,000 baht (S$10,900) in cash.

The man, aged in his 30s, spent about one minute robbing the Bang Khlo Laem branch at about 8.52am.

A witness told police that the man wore a hair net that motorcyclists sometimes wear under their helmet.

Police Major-General Surachai Kuandechakup, the deputy metropolitan police commissioner, said the suspect approached the teller and showed an undetermined model of gun and demanded that he give him money.

"The suspect told the teller that he was sorry and he had money problems," Surachai said.

He then put the money into his bag and walked out of the bank quietly.

The security guard even opened the door for him, assuming that he was just a hired messenger.

Surachai said that judging from what the suspect told the teller, he was not a professional criminal.

A bank security guard told police that the robber looked familiar and could be a bank customer.

Wat Phrayakrai police are checking the bank's security cameras to try and identify the robber and create a sketch. Some witnesses said they clearly saw his uncovered face. Police say the gunman wore a black T-shirt and black trousers.

He entered the bank carrying a bag and behaved like a typical customer.

The suspect then drew a gun on the teller and demanded cash.

After leaving, he was seen fleeing towards Rama IX Bridge. Five employees and a cleaner were in the bank at the time.