Berlin's Senator for Economy, Energy and Enterprise, Franziska Giffey (SPD), has been injured after an attack in a library in the Rudow district of the German capital.
Giffey had to be treated in hospital as a result.
What authorities have said
A man suddenly "attacked the former mayor from behind with a bag filled with hard contents and hit her on the head and neck" in a library on Tuesday afternoon, police and the Berlin public prosecutor's office said on Tuesday night.
The state police have since taken over the investigation.
Giffey, from the center-left Social Democratic Party and a former Berlin mayor, "briefly went to hospital for outpatient treatment for head and neck pain," police and the prosecutor's office said in a statement.
Berlin's Senator for Sports Iris Spranger "strongly" condemned the attack "on Franziska Giffey and on other politicians and election workers, all of whom are committed to a democratic debate."
"The state and federal police forces are doing everything they can to protect politicians. The conference of interior ministers agreed yesterday at the special session that democracy must be protected more effectively against hate speech and false information."
"The protection of individuals from such attacks under criminal law also serves to protect democracy itself."
Local lawmakers increasingly insulted, threatened, attacked
Pattern of attacks on politicians
The incident comes just days after an attack on the European lawmaker Matthias Ecke and a Green Party campaign worker in Dresden.
Ecke, a member of the European Parliament for Chancellor Olaf Scholz's SPD, was set upon by four attackers as he displayed EU election posters in Dresden on Friday night, according to the police.
jsi/kb (AFP, dpa)