A hospital in Henan province where a patient killed three people with a chopstick has been closed to allow for an investigation into its standards.

The man, identified as Yang, attacked four women at the privately run Da Zhong Hospital after breaking free of his restraints on Feb 24, according to a statement from the Luoning county government on Tuesday.

All of the victims were patients. One of the women died at the scene, while two others died in hospital from their injuries.

The mental health hospital is "suspected of chaotic management" and has been closed while an investigation team looks into the attack, the statement said. It added that two county health officials in charge of supervising local hospitals have been dismissed.

"The county's public security authority has placed Yang under criminal coercive measures and a thorough investigation is ongoing," the government said without elaborating. Coercive measures can include detention and 24-hour monitoring.

The killings, first reported on Saturday by The Paper, a news website based in Shanghai, happened on the night Yang was admitted to the hospital.

"Yang is a schizophrenic," The Paper quoted an anonymous source at the hospital as saying. "He looked potentially dangerous during a health check after he was admitted, so we treated him as a priority patient. We asked his relatives to look after him and assigned a member of our staff to regularly observe him."

Yang refused to take medicine or meals, "and we had to fasten him to his bed with restraints", the source said.

On Tuesday, nine minutes of footage from a surveillance camera at the hospital that captured parts of the attack began to spread on social media.

In the video, a man believed to be Yang is lying on a hospital bed and appears to free his hands from restraints at 8:21 pm. Seven minutes later, he picks up a chopstick from a nearby table and walks off-camera into another room shared by two of the victims.

He then returns to the room about 30 seconds later and is seen stabbing two other women in the head with the chopstick.

According to The Paper, the last time a staff member checked on Yang was at about 5:30 pm, even though the hospital said such checks were carried out every half hour.