The incident happened at around 8.30am at a railway station in Unterfuehring, a municipality in Upper Bavaria.
According to preliminary reports, police were called to the station to respond to a report about a brawl on the platform. In the confrontation that followed, the shooter snatched a gun from one of the officers and used it to shoot a policewoman in the head.
The shooter also received a gunshot wound, and it is unclear who fired the first shot. He also shot two more passers-by in the arm and leg.
Suburban train station #Unterföhring – Several persons wounded by gunshots. Police woman seriously wounded. One person has been arrested.
— Polizei München (@PolizeiMuenchen) June 13, 2017
The policewoman, 26, is in a critical condition in hospital. The two passers-by have non-life threatening injuries, as does the perpetrator, who was wounded as he was apprehended by police.
A police spokesman told the German newspaper Die Welt that the 37-year-old shooter was a homeless man who had been born in Upper Bavaria.
"The situation in Germany is really worrying; not a day goes by without some incident involving Islamic terrorism or some people who somehow get a hold of weapons and start shooting," Rar said.
"The election campaign is just beginning (Bundestag elections take place in three months) and of course, people are paying particular attention to the work of the police and politicians. The issue of internal security is becoming almost the central issue on which people are judging politicians and expecting action."
"Here I must say that the Christian Democrats, Merkel's party, understand the situation. They are doing all they can to at least create the appearance of a fight against crime and terrorism, perhaps in contrast to other parties, which as before remain without any initiative," Rar said.
The train station shooting follows several incidents of shootings at German train stations.
On July 18, a 17-year-old asylum seeker who claimed to be from Afghanistan attacked passengers on a train in Wuerzburg, Bavaria, with an axe. The man was shot dead by police after wounding five train passengers.
On Monday, Germany opened its federal conference of state interior ministers in the city of Dresden, their final meeting before federal elections on September 24. Ministers discussed granting more powers to the police such as random stop and searches and the digital surveillance of terror suspects.
Increased security measures are supported by federal Interior Minister Thomas de Maiziere, who has proposed similar measures and called on states to come up with a unified policy.
"There should not be two different zones of security in Germany," de Maiziere told Germany's ARD broadcaster.
