I suspect that in the first instance emergency protocol set in: If you're a lighting op, in an emergency you turn all the lights on full and if you have moving lights, which they did, you aim them at the audience in order to help them see to evacuate. When it became trully apparant what was happening someone probably took the decision to turn them off. The Lighting OP would have been at the back of the auditorium, any number of people/security were probably screaming at him to cut the lights once they realised they were targets.Posted by JoefromtheCarolinas (here)
Why in the world would the guys working lights turn the entire house UP during the shooting, then turn them off when People were trying to help the allegedly wounded? To light up the targets?