HONGKOU District police have detained a man who went berserk yesterday and allegedly beat up four people, including an 84-year-old man who suffered severe head injuries.

Police said the suspect, a 46-year-old migrant worker surnamed Huang, had no record of mental illness. He has undergone a drug test.

The other three victims suffered broken bones and bruises and were all in a stable condition in hospital yesterday, police said.

The elderly man is in a serious condition.

The outburst happened about 6am yesterday. Huang alighted from a taxi in Feihong Road and started to chase and beat passersby, witnesses said.

"He first quarreled with the driver in the cab and refused to pay the fare, even demanding money," said the owner of a nearby news stand.

"Then he walked here and asked everybody for money."

After Huang was refused cash by several people, "he beat everyone he saw," said the news stand owner, who was also slapped by the suspect.

"The man was very violent," said another witness.

"He kicked a passerby after knocking him down."