Marston Hefner, Hugh Hefner's son, was arrested for allegedly attacking a Playboy Playmate Sunday night.

Marston Hefner, the 21-year-old son of Playboy magazine founder Hugh Hefner, allegedly attacked his 20-year-old girlfriend, 2011 Playmate of the Year Claire Sinclair late Sunday night, TMZ reported.

Marston Hefner allegedly punched and kicked Sinclair, leaving bruises and red marks on her body, sources told TMZ, and police officers appeared after Sinclair called family members, who proceeded to call 911.

Marston Hefner admitted that the two had fought that day, but denied the charges and was released on $20,000 bail several hours after he was arrested, The New York Post reported.

Sinclair has obtained an emergency short-term restraining order against Marston Hefner after the incident, TMZ said Monday, adding that Sinclair told the web site that she plans to move out as soon as she can.

She went on to tell TMZ that she called Hugh Hefner after the alleged attack, and said that he said he was very disappointed in his son and sympathetic toward her.

Hugh Hefner previously said that Sinclair, who became Playmate of the Year last year at the age of 19, reminded him of Bettie Page, according to Fox News.

Sinclair tweeted a message on Monday that seems to address the alleged attack: There's two types of pain in the world--pain that hurts you, and pain that makes you stronger. All of your positivity is giving me strength.