Two e-bike repairmen have been detained for allegedly trapping customers with knife blades on the street, police said on Monday.

Investigation started in the middle of last month when police in Yangpu District received a report from an angry resident who found out about the trick.

The resident, a man surnamed Chen, said his e-bike had had several flat tires recently when he rode on Huangxing Road, and the cuts on the tires seemed to be caused by knife blades.

With this doubt, Chen used a magnet stone to detect suspicious objects on the street and found a few pieces of knife blades.

Police found that the knife blades were either inserted in cracks on the road surface or fixed to the ground with fruit skin.

From street surveillance cameras, police spotted a suspicious man on an e-bike who in several instances rode slowly and stopped once in a while to tap the ground with his feet.

The man appeared again on the afternoon of May 31 and was caught by the police on the scene. Police said they found several pieces of knife blades from his e-bike.

The suspect, surnamed Chen, who runs an e-bike repair shop nearby, has allegedly confessed.

A man surnamed Huang who works in Chen’s shop and allegedly joined him in the scheme, has also been detained.