Authorities have charged a man with leaving a 13-month-old girl alone in a tent at the Occupy D.C. camp.

Officers were called to McPherson Square Wednesday morning after other people living in the park heard the girl crying, Sgt. David Schlosser, a U.S. Park Spokesman confirms to Fox News.

Police believe the girl had been alone for at least a half hour wearing just a onesie on a rainy day when the temperature was in the mid-40s.

The girl was checked by medics and placed in the custody of the D.C. Child and Family Services Agency.

About 30 minutes later, a man approached officers claiming to be the child's father. He was arrested and charged with attempted second-degree cruelty to children. Police have not identified the man but said he had a tent in the Occupy encampment. 

"None of us knew this person," Kelly Canavan, a protester who has been living at the camp told Washington Post. 

"It was a despicable, atrocious thing to do. Everyone here is revolted by the behavior," she said. 

Click here to read more from The Washington Post. 

The Associated Press contributed to this report.