Alyson Hannigan was among those witnessed a physical altercation between Arnold and Burnett Sunday night at a fundraiser for the Motion Picture Television Fund in Century City. "Walked n2 party behind Tom Arnold and saw him & Mark Burnett get into a fight!" she tweeted. "Thought it was a joke until security jumped in! #WhyIstayhome." Variety reports "a source with knowledge of the situation said it involved shoving but it was unclear who made the first move." Arnold, whose Viceland series The Hunt For The Trump Tapes premieres Tuesday, has been publicly feuding with Burnett over unreleased Apprentice tapes of Trump allegedly making racist and sexist remarks. Arnold tweeted: "Mark Burnett just went apesh*t & choked me at this huge Emmy party then he ran away with his torn Pink shirt & missing gold chain. I’m waiting for LAPD." An hour later, Roma Downey posted a picture of her hand, tweeting: "Got this bruise tonight when Tom Arnold tried to ambush my husband Mark and me at a charity event. Is your TV show worth it Tom? Please stop." Arnold responded to Downey's tweet: "Bullsh*t. You lie your crazy husband attacked me you psycho. I’m filing police report & suing you for defamation." Arnold also tweeted there is tape of the incident. Burnett could not be reached by Variety for comment. ALSO: Arnold claims that The Apprentice tapes were handed to Ronan Farrow on Sunday.