"There was an incident that occurred at 2 a.m. at 99 Prince [Street]," a NYPD spokesperson tells PEOPLE. "It's all under investigation by the police department … People will come in sometime this afternoon [to be questioned].
New York's Daily News reports that Proenza Schouler women's wear designer Jack McCollough – a friend of Shields's – interrupted her and Sutherland while they were speaking outside the SoHo nightspot SubMercer, resulting in an agitated Sutherland allegedly headbutting McCollough after the two men exchanged words.
Witnesses also say Shields was shoved but not hurt. All were out for an after party following the Met's Costume Institute Gala, and a rep for Shields denied she had anything to do with the alleged headbutting. "Nothing happened to her ... Jack did nothing inappropriate. It's not clear what caused Kiefer to do what he did," the rep told TMZ.com. An attorney for Sutherland had no comment.
McCollough reportedly received a minor cut on his nose. The designer is quoted as telling authorities that Sutherland "was drunk and obnoxious and wouldn't back down or be logical," and that the actor "pulled this stupid wrestling move like a teenager" before the headbutt. An attorney for Sutherland had no comment.
Police and friends of Sutherland's told the News that Sutherland was intoxicated. The paper says that both Sutherland, 42, and Shields, 43, are expected to speak to the police on Wednesday.
Sutherland recently served a seven-week sentence for his second DUI.
The incident was first reported on N.Y.C. nightlife blog Guest of a Guest.
Reporting by LIZ McNEIL