A knife-wielding man injured four people in a renowned hospital in Shanghai on Saturday, before being shot and injured by security forces who managed to subdue him, police said.

Calls for help from Ruijin Hospital, located in the center of the Chinese economic capital, were received at the end of the morning by the police who immediately dispatched agents.

"Police quickly arrived on the scene and found a man holding a group of people hostage with a knife on the seventh floor of the hospital," police said in a statement.

"When the suspect attempted to attack the hostages and officers, police opened fire to wound and subdue him," the statement added.

Four people were injured and were placed in care without any vital signs being visibly threatened, said the police.

The motives for the assault remain unclear at this time.

On videos published by Chinese media, we see the police entering a closed room of the hospital. Another video, which is circulating extensively on social media, shows the public fleeing the building.

Mass crimes are rare in China where the carrying of firearms is strictly prohibited, but stabbings do occur occasionally.