A South Korean-born former U.S. gang member has been arrested for robbing a Seoul bank, police here said Friday.

The 38-year-old suspect, identified only by his initial A, allegedly attacked a bank security guard at a Woori Bank in southern Seoul's downtown Gangnam area at around 4 p.m. Thursday, the Suseo Police Station said. He took a gas gun from the knocked down guard and robbed some 20 million won ($ 17,500) from a bank teller.

The suspect then attempted to flee by taxi but was arrested at the scene after the taxi driver refused to take him anywhere, according to the police.

The security guard and the taxi driver were taken to a nearby hospital to be treated for minor injuries. the police added.

The suspect was adopted to the U.S. when he was 1-year-old but was unable to get U.S. citizenship as his adoptive parents passed away shortly after, the police said. He was deported from the U.S. in 2007 after serving a prison term for drug charges as a member of a criminal gang active in the state of Arizona.

"The suspect worked as an English teacher in Seoul but lost his job when his employer found out about his criminal record," a police officer close to the investigation said. "He acted as if he does not speak Korean throughout the investigation." (Yonhap)