Four people at a renowned Shanghai hospital were wounded by a knife-wielding assailant on Saturday, in the second reported stabbing incident after a Covid-19 lockdown of the financial hub was lifted early in June.
Officers raced to the more than 100-year-old Ruijin Hospital on Saturday morning after receiving calls about an attack, police said.
Videos on social media showed chaos as visitors clambered under turnstiles to get out of the hospital while doctors were seen running out with their patients, some in wheelchairs and one on a mobile bed.
A long trail of blood was seen on the marble surface of a flight of stairs in one video.
"It's very shocking," said a Shanghai resident who had arrived for a check-up just after the hospital was sealed off, declining to give her name. "This is very despairing. What has happened to this society?"
Hospitals are a flashpoint for many in China, who face issues from touts illegally trading appointment tickets, long queues to see doctors, and corruption that can push up the cost of receiving care.
Reports of patients assaulting doctors are also common.
At the Shanghai hospital, police found a man holding a crowd hostage with a knife on the seventh floor of the outpatient department. When the man threatened to hurt the hostages, the police opened fire, subduing him, according to local police.
None of the wounded is in a life-threatening situation and the incident is being investigated, the police said.
Ruijin Hospital has been cordoned off, and all appointments cancelled, a police officer told onlookers outside.
A man was arrested on Monday after going on a stabbing spree in the city's downtown Jingan district.