A knife attack at a hospital in Shanghai, China has left four people injured, officials said.

This is the second stabbing incident that has been reported at the 100-year-old Ruijin Hospital since COVID-related restrictions were lifted last month, Reuters reported.

Police responded to the scene after receiving calls about a possible knife attack at the hospital, where they found frightened staff and a bloodied crime scene.

Shanghai China hospital

Police officers stand outside the outpatient department of Ruijin Hospital following a stabbing incident, in Shanghai, China July 9, 2022. REUTERS/Brenda Goh (REUTERS/Brenda Goh)

Videos taken at the scene show doctors, nurses and other staff members fleeing the hospital with their patients.

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One witness described the situation as "very shocking" and "very despairing," Reuters reported.

According to the report, knife attacks at hospitals in China have become more regular.

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Shanghai China hospital

Police officers walk outside the outpatient department of Ruijin Hospital following a stabbing incident, in Shanghai, China July 9, 2022. REUTERS/Brenda Goh (REUTERS/Brenda Goh)

"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," Reuters reported.

Subsequently, attacks on staff members and doctors are also somewhat common, per the report.

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Shanghai China hospital

Police officers stand outside the outpatient department of Ruijin Hospital following a stabbing incident, in Shanghai, China July 9, 2022. REUTERS/Brenda Goh (REUTERS/Brenda Goh)

Police closed off the Ruijin Hospital following the attack and administrators have canceled all appointments, Reuters reported. Police are investigating.

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The waterfront city of Shanghai is the country's biggest city.

The victims' conditions weren't reported.