Police ordered the immediate evacuation of the BUKO Stadion in Velsen-Zuid after the final whistle on Saturday evening, according to ESPN, among others.
Earlier on Saturday evening, Telstar and Feyenoord had fought out a fierce contest at the BUKO Stadion. The Rotterdam side eventually edged it 3-4.
After the final whistle, police began evacuating everyone in the stadium. They cleared the entire ground following the press conference.
Local police then taped off the entire stadium. A specialist team arrived and examined a smoke bomb lying beneath the stand.
Shortly after midnight, the smoke bomb had been secured and the BUKO Stadion was cleared for use again, according to a police statement.