The attack occurred immediately before a meeting of the towns urban planning committee where migrant issues were due to be discussed. According to police, the mayor had returned to his car to retrieve a laptop. As he leaned in, someone approached him and struck a blow to his head with either a club or a plank of wood, knocking him to the ground.
http://www.breitbart.com/london/2016/10/01/migrant-centre-plans-tiny-german-town-mayor-attack-bomb-scare/