Police are investigating after a 12-year-old girl was sexually assaulted inside a building at NYCHA’s Cooper Park Houses in Williamsburg, according to the NYPD. Officers say a 911 call came in around 5:45 p.m. Thursday reporting the assault. When police arrived, they learned the girl had been attacked inside the building. She was taken to a local hospital and is stable , officials said. Crime scene units and detectives were seen at the complex throughout the night, collecting evidence from the lobby and stairwell. Investigators placed evidence markers and worked to identify clues that could lead them to whoever’s responsible. Police have not released a description of the suspect or said whether the victim knew her attacker.