NEW YORK, New York (X17online) - Kiefer Sutherland reportedly headbutted Proenza Schouler designer Jack McCollough at a party following Monday night's Costume Institute Gala, according to the New York Daily News.

The altercation was reportedly sparked after the designer pushed Brooke Shields. Kiefer demanded an apology (apparently he was trying to protect her honor) and when McCollough refused, that's when things got physical.

Now here's the strange part, some reports say that McCollough and Brooke are actually great friends (she's often seen wearing Proenza Schouler on the red carpet) and that Kiefer's actions are just plain nuts! Brooke's peeps are even defending McCollough saying it was a big misunderstanding and that "nothing happened to her."

McCollough, for his part, is claiming that Kiefer was "drunk and acting obnoxious and wouldn't back down or be logical."

It's apparently well known around Hollywood that Kiefer can be kind of a hot-head when he's had a few too many.

Cops are investigating the incident. They're expected to interview all the parties involved by the end of the week.

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