Berlin: Police made two arrests after a 30-strong group of well-organised Cologne fans dressed all in white stormed onto the pitch after their team`s last-minute Bundesliga defeat to Borussia Moenchengladbach.
A 91st-minute header from Swiss midfielder Granit Xhaka sealed Gladbach`s 1-0 win in the Rhine derby, but a group of fans reacted angrily by storming out of the Cologne fan block and past stewards.
Flares were thrown onto the field in the chaos and the group scuffled with security staff and police on the pitch while an officer was hurt before order was restored.
With the German Football Association (DFB) set to investigate, Cologne has promised to "do everything in our power to identify and punish the perpetrators".
The game had to be halted on several occasions while Cologne fans fired flares and home coach Peter Stoeger was shocked by the scenes.
"What can I say? Anyone who loves football can`t have anything to do with something like this," said the 48-year-old Austrian.
"This is as bitter as the 1-0 defeat."
Gladbach coach Lucien Favre was just as damning.
"This is something which has nothing to do with football."
Cologne are 11th in the German league while the win puts Borussia third in the table.