Passersby and an off-duty police officer nabbed one of two thieves running away after a bag snatch in Kowloon on Thursday. They helped recover HK$4 million (nearly US$510,000).

A 53-year-old man went to a currency exchange shop on Tak Man Street in Whampoa just before 6pm to withdraw HK$4 million in cash and put it into his backpack, news website HK01.com reported.

Two suspects carrying a knife came up behind the man on Hung Hom Road and snatched his backpack and ran away. The victim was wounded on his hands and left leg.

Two staff at the nearby Pizza Hut shop heard yelling and ran out from the shop to chase the suspects. An off-duty police officer who witnessed the incident also joined the chase.

One of the suspects, a 20-year-old Indian man was subdued by the three men but the other suspect got away.

Police officers arrived and sent the victim to hospital. They found a knife in the suspect’s backpack and also recovered all the stolen money.

Police said the arrested Indian came to Hong Kong three years ago and held a permit for a temporary stay, Apple Daily reported.

They are hunting the second thief who is also a South Asian man, aged around 20 to 30. They said he had a beard and was wearing a cap, a black long-sleeved shirt, dark-colored pants and blue sneakers when the robbery happened.