ASSISTANT producer Mr Koh Chee Kaur thought it was a scene being filmed for a movie or TV serial when he spotted two policemen chasing an armed robber across a busy road at Jurong East Avenue 1 on Thursday afternoon.

He was riding his bicycle towards Jurong West and only realised it was real when one of the policemen signalled an SBS bus to stop before continuing with the chase.

'I gave chase in the opposite direction and the robber almost crashed into me,' recalled the 24-year-old at the Clementi police division headquarters on Friday morning.

Mr Koh stuck out his left leg and tripped the 34-year-old robber, who fell to the ground. He was then arrested by the police.

Half an hour earlier, the robber had entered a lift at Block 341 with Madam Noriah Gemahat, 51, where he whipped out a paper-cutter and demanded she hand over her gold necklace.

A struggle ensued and moved to the lift landing of the 10th floor where the pint-sized Madam Noriah lives. The robber, dropped the necklace, worth $1,000, and fled after Madam Noriah's husband came to her aid when he heard her cries for help. The couple then called the police.

Madam Noriah said that she risked her life for the necklace as she received it as a gift from her mother about 40 years ago.

'It is precious to me so I used kungfu on the robber,' she added in Malay.

For his public-spirited efforts, Mr Koh was presented with a plaque by the police.