A woman has been arrested after four people were found dead and another seriously injured at a hospital near Berlin.

The dead and injured were reportedly patients at the specialist orthopaedic clinic.

“The victims showed signs of significant external violence,” police spokesman Thorsten Herbst told The Associated Press.

Mr Herbst said the detained woman was “urgently suspected” of the killings, but declined to provide further details.

A 51-year-old woman who works at Oberlinklinik hospital is under provisional arrest under suspicion of being the perpetrator.

The motive is unclear. The woman’s identity has not been released.

A spokesman for Brandenburg state police said officers were called to the clinic shortly before 9pm on Wednesday (local time).

“A total of four people with fatal injuries and one other seriously injured person were found in various hospital rooms in one ward,” police said.

An initial survey of the scene indicated that all the victims’ injuries could be traced back to “severe external use of force”, the statement said.

Potsdam is the capital of Brandenburg, the state that surrounds the German capital. According to its website, the Oberlin Clinic has 160 beds and 300 staff.

The Tagesspiegel newspaper reported the incident occurred at a unit where people with mental development issues are treated for muscle and skeletal illnesses.

-with AAP