An 18-year-old schoolgirl and a man have been killed following a violent ‘domestic incident’ in northeastern Germany.

Police were called to a secondary school in the town of Gosen-Neu Zittau, near Berlin, on Thursday at around 1.45pm after receiving several phone calls reporting an attack.

Brandenburg state police have confirmed a 19-year-old German considered a ‘prime suspect’ in the case has been arrested; however, it is not yet known if he is a student at the private Docemus Privatschulen school.

The female victim is reportedly a student at the school, according to the RBB (Berlin-Brandenburg Broadcasting).

In a statement, police said two ‘fatally injured people were found at the scene,’  adding they currently believe the incident is ‘linked to a relationship, not a random act’.

It is understood the 30-year-old male victim reportedly died while trying to aid the girl, but the force has not specified whether a knife or other weapon had been used.

Ulrike Liedtke, the speaker of Brandenburg’s regional parliament, described the killing as a ‘cowardly femicide’.

Ms Liedtke said: ‘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.’

State premier Dietmar Woidke described the attack as an ‘unimaginable act of violence’.

He said: ‘Our schools should be a safe haven for our young people. Here, a school has become the scene of an unimaginable act of violence.’

Images from the streets surrounding the institution showed multiple emergency service vehicles attending, while two rescue helicopters were also deployed.

On Thursday evening, around 70 children and adults attended the scene with flowers and candles for a memorial service, according to German national paper Die Zeit.

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

However, the school will remain open for students who wish to attend, reports German newspaper, MAZ.

Emergency chaplains are also said to be on site offering support to students, teachers and family members.

The attack comes only one month after two girls were seriously wounded and a 16-year-old suspect arrested following an attack at a secondary school in the southern German state of Bavaria.

The perpetrator appeared to have deliberately targeted the Welfen grammar school in the town of Schongau in a suspected ‘rampage’, a police spokeswoman told AFP.

She was unable to confirm press reports according to which the assailant used a knife in the attack.

More than 15 patrol cars were dispatched to the Welfen-Gymnasium in Schongau, southwest of Munich.

The incident is believed to have taken place partly outside and partly in the immediate vicinity of the high school.

The alleged perpetrator apparently attempted to flee the scene but was apprehended a short time later.

Security sources initially reported four injuries, however, at the time police said ‘several people’ were injured without giving an exact figure.