An RB Leipzig fan has said police "underestimated" the potential for violence after an attack by Borussia Dortmund supporters ahead of Saturday's match at the Westfalenstadion.
Visiting supporters were attacked by a group of Dortmund fans near a beer garden close to the stadium's away entrance.
Around 1,000 of the 8,000 Lepzig fans had made the trip on a chartered train, arriving at a station to the south of the Westfalenstadion. They were making their way to the away entrance on the northern side when the violence happened.
After the supporters arrived at the street leading towards the stadium they were attacked in front of the Rote Erde beer garden, around 300 metres from the away entrance.
"It was a typical RB crowd. Old, young, women, kids," a Leipzig fan told ESPN FC, adding that police had appeared "understaffed" at the station.
"They [the Dortmund fans] were aggressive and attacked everyone who was wearing red and white [the Lepizig colours]," the fan said. "They even had a go at children.
"Police and BVB certainly underestimated the potential for violence."
Footage published on social media platforms showed stones and bottles being thrown in clashes that saw around 10 Leipzig fans and four police officers injured.
Cornelia Weigandt, a Dortmund police spokesperson, told ESPN FC the force had rated the match as one with a "heightened risk" but did not believe it was "high risk" because of the information obtained beforehand.
"We have no legal handle to welcome the fans with a major police force," she said of the situation at the railway station. "No danger was to be expected from them [the Leipzig fans]."
Weigandt said one of the injured officers had been hit with a crate, while another one was bitten.
In a statement released on Sunday, BVB said they "were working with police to deal with the incidents" and said they "strongly condemn the violence."
German Home Secretary Thomas de Maiziere told Bild that people "who throw stones and crates of beer at police, and do not even take into account families or children, do not belong in the stadium but under lock and key."
Meanwhile, the German FA has opened proceedings against Dortmund for defamatory banners about Leipzig that were unveiled on the Sudtribune prior to kick-off.