ZHENGZHOU -- A man has been detained for attacking and killing a policeman in central China's Henan province on Wednesday morning, local authorities said.

One policeman was killed and another two injured in Luoyang City, when the knife-wielding man, surnamed Deng, assaulted them at a crossroad at around 7:40 a.m., according to the local public security bureau. A senior citizen was also injured in the panicking crowd.

Deng, a Luoyang resident, was punished by police on Tuesday for violating traffic rules while riding a three-wheeled motorcycle, police said. It is not clear if Deng attacked out of revenge.

The injured are receiving treatment in hospital.