The incident started when several flares were set off near the pitch for a pyrotechnic display. It’s unclear whether this was planned by Ajax or the fans. Once these flares went out, an unplanned fire and thick smoke was visible from the bottom of the stand.

It appears one or several of the flares caught a banner, which fed the flames. The fire was extinguished but not before a significant amount of smoke filled the stand. It’s unclear whether anyone injured by the worrying flames or dangerous smoke.

The game at the Amsterdam Arena later got underway. The fixture, known as De Klassieker, is one of the biggest events in Dutch football. It is not technically a derby, as Ajax are based in Amsterdam and Feyenoord are based in Rotterdam.

Ajax are widely regarded as the biggest club in the Netherlands. They’ve won a record 35 Eredivisie titles, a record 20 Dutch Cups and nine Dutch Super Cups. It’s their success in Europe, however, that gives them such a status – winning four Champions Leagues, two UEFA Super Cups, the UEFA Cup and European Cup Winners’ Cup.

Feyenoord are arguably the country’s second-biggest club, something PSV Eindhoven may contest. They were crowned Champions of Europe in 1970 and have won the UEFA Cup twice. They’ve also lifted 15 Eredivisie titles, 13 Dutch Cups and four Dutch Super Cups.

Are Ajax one of the biggest clubs in Europe? Let us know in the comments below!

Sunday afternoon’s De Klassieker was particularly important, as there were just eight points separating leaders Ajax and Feyenoord in third heading into the game. Ajax are the defending champions, while Feyenoord have won just one league title this century.