Rangers and Celtic fans clash on the field after Scottish Cup tie

GLASGOW, Scotland (AP) - Fans invaded the field and clashed after Celtic beat Rangers in a penalty shootout in the Scottish Cup quarterfinals on Sunday.

Supporters from both teams ran down from the stands at Ibrox with flares thrown and several altercations before the situation was brought under control.

Celtic won the shootout 4-2 to advance to the semifinals after the game ended 0-0. Tomas Cvancara's winning spot kick sparked wild celebrations from the away fans, with some running onto the field.

Hundreds of Rangers fans then followed on, with missiles thrown and police and stewards having to form a barrier to restore order.

"Nobody wants to see this in football," Rangers manager Danny Rohl told Premier Sports.

"It's unfortunate. Hopefully it doesn't dilute the performance," Celtic manager Martin O'Neill added.

The Scottish Football Association said it had launched an investigation into the incident.

"The Scottish FA condemns the behaviour from supporters entering the field of play," the governing body said in a statement, adding that "an investigation will be carried out immediately."

The rivalry between Rangers and Celtic is among the fiercest in the sport, with the Glasgow giants long-dominating in Scottish soccer. But this season has seen Hearts lead the way in the Scottish league, leaving Rangers and Celtic playing catch-up.

"Old Firm games, they are explosive games. They always have been. That's maybe one of the reasons why the derby is one of the best in the world," O'Neill said.