Dundee manager Tony Docherty: "I want to make sure that never happens again. I was really disappointed - if you're losing 2-0, keep it 2-0 don't lose three, four, or five.
"I can't be too hard on the boys because they have been fantastic. We've had healthy home form and we've been competitive in every match. Tonight, things just ran away from us.
"The Old Firm have the quality when they get their tails up , to pick you off and that's what happened tonight."
Asked if he thought the game might be postponed Docherty said: "I did because it got to the stage it was such a delay and such a problem in terms of preparation. Then what happened with the pyros it's difficult getting it again.
"But I've got an honest group of boys who won't make that as an excuse because it's the same for both teams.
"But when I see a performance I haven't seen from my team this year, maybe there's a reason for it.
"When it gets to the stage when you almost get a game abandoned, I think action has to be taken.
"I did think at that stage after speaking with the police, and the fire alarms were going off, I did think the game was going to be postponed."
Docherty says he received an explanation from the fourth official about the fourth goal, where referee Kevin Clancy blocked Luke McCowan, before Rangers went up the pitch and scored.
He says the referee has to actually touch the ball for play to be stopped.