The Chinese Police in Beijing are investigating claims that children were sexually abused and pricked with needles at a kindergarten, China’s official Xinhua news agency reported on Thursday. A few teachers at the RYB Education New World kindergarten were suspended after the allegations were made.

The issue came to light after several parents raised concerns online about the alleged sexual abuse about a bilingual class of 20 students and four teachers. The parents filed a police complaint on Wednesday, Xinhua reported.

“Disobedient students were also forced to stand naked or were locked up in a dark room at the kindergarten,” an unidentified parent told news outlet Caixin. Another parent told Xinhua that some children were told to take two pills after lunch and she was unsure whether her child was sexually assaulted as the three-year-old was “too little” to recount details.

Beijing Police said they had carried out forensic tests and obtained CCTV footage of the school for the investigation.

The kindergarten was open on Thursday, but few students showed up. Some parents waited outside its gate, demanding an explanation from authorities. Cui Lijun, brand director of RYB Education kindergarten, told the state-run People’s Daily that there was no evidence to support the claims of sexual abuse, so far.