Two people have been killed in a “domestic violence incident” at a school in the town of Gosen-Neu Zittau near the German capital Berlin, local police have said.

Brandenburg state police said they arrested a 19-year-old German man, who is “considered a prime suspect”. They said it was not a “mass shooting”, without specifying what weapon was used.

It is not yet known if the suspect was a student at the private Docemus school.

One of the dead was an 18-year-old secondary school female student and the other victim was a 30-year-old man who died when he tried to intervene, local media reported.

The arrested suspect is believed to be the ex-boyfriend of the 18-year-old victim, Maz Online reported.

Ulrike Liedtke, the speaker of Brandenburg’s regional parliament, called the incident a “cowardly femicide”.

“The fact that we once again had to witness deadly violence against a woman fills me with deep sorrow and anger.

“I am shaken that a citizen who showed moral courage and wanted to help also lost his life in this terrible act,” Liedtke said.

State premier Dietmar Woidke said it was an “unimaginable act of violence”.

The school’s managing director Michael Kunz said classes will be cancelled on Friday.

Although there would be no regular classes, Kunz said the school would remain open for all students who wished to come.

“We want to provide them with a safe space where they can come together, talk to each other, and process what has happened,” he said.

A “very careful” decision will be made in coming days about how school life will be structured, he added.

Last month in a separate attack, two girls were seriously wounded and a 16-year-old suspect arrested at a secondary school in southern Germany.