A Chengdu restaurateur has described the terrifying moment he confronted a man on a knife rampage.

Luo Guangquan was outside his eatery on Sunday night when a man in his 20s stabbed a family, including their baby, in the Sichuan provincial capital's western suburbs.

Armed police on the scene shot the attacker shortly after and he was then detained.

"It was like something out a crime movie," Luo said on Tuesday. "I was terrified."

The 45-year-old said the man took a seat outside his restaurant in Yingkang Road at 9:35 pm.

"He looked drunk, and I could see he was holding a kitchen knife in his right hand," he recalled. "I was suspicious, so I told an employee to call the police."

A minute later, the man stood up and stabbed an 18-month-old girl who had been playing nearby.

"She was outside the restaurant with her mother. The man stabbed her in her right arm and chest," Luo said. "Her mother rushed over and grabbed the child, but before she could get away she was stabbed in her back twice.

"I threw my chair at the man, but I failed to hit him. He then stabbed a 12-year-old girl as he attempted to run away."

Luo said about 30 police officers soon arrived and the attacker was shot twice, "once in his right hand, which was still holding the knife, and once in his right leg".

Police have not released any information about the man's identity or motive.

Before the incident outside Luo's restaurant, police said the man had also attacked three other people in a nearby road.

None of the victims' injuries were life-threatening, although doctors at Sichuan Provincial People's Hospital were on Tuesday working to save the 18-month-old girl's right arm.

The child's father, Zhong Ming, who runs a home decor store close to Luo's business, also received minor injuries during the assault in Yingkang Road.

It was the second stabbing incident in Chengdu in less than two months.

On Aug 25, a farmer from Jintang county killed four people during a random stabbing in the street.