She said she and other parents allegedly found multiple needle marks on their children's bodies, adding that the kindergarten and the police had not allowed them to review videos from the school's surveillance cameras.

"My child said the teacher told them it was a secret and they were not supposed to tell anyone else including parents," the mother said. "She now bursts into screaming at night, saying: I'm not sick, why do I have to get a shot?"

The Xinhua state news agency reports that Beijing police have performed forensic tests and obtained surveillance camera footage from the kindergarten.

Kindergarten apologizes, promises 'zero-tolerance' policy

The kindergarten is run by RYB Education, a Chinese company listed on the New York Stock Exchange.

It operates in about 300 Chinese cities and has about 1,300 day care centers.

It announced the suspension of several teachers, and apologized to the parents and public for "causing serious worries" in a statement released Friday.

"We have provided the relevant surveillance videos and equipment to the police," it said. "Before a clear conclusion can be drawn, our priority is to help the students and their parents emotionally, and try to minimize the impact of the incident on the children."

CNN's repeated attempts to seek direct responses from the kindergarten and local educational officials on site were thwarted by security guards, who said no one would make additional comments beyond previously issued statements.

As more horrific details emerged, the government scrambled to respond to the incident. Both the national education ministry and the municipal education authority in Beijing have pledged cooperation with the police and swift investigations on their own, with local officials sending a team to the kindergarten.

The company said it plans to keep the kindergarten open, promising to uphold a "zero-tolerance" policy toward child abuse and shoulder responsibilities pending the result of the police investigation.

The statement also said the head of the kindergarten involved had filed a police report that alleged "false accusations and being framed by certain individuals" - without specifying who.

It was relatively quiet around the RYB Xintiandi campus Friday, with some parents and onlookers gathering outside the gate where a copy of the corporate statement was posted.

One grandfather, who had just picked up his granddaughter but declined to be named, told CNN that the 4-year-old mentioned her classmates being forced to take white pills for disobedience and everyone was told to keep it a secret.

Another resident of the neighborhood who identified himself as Mr. Liu said the kindergarten is the best in the area and costs as much as 5,000 yuan ($750) a month for bilingual class students. He said he was furious upon hearing the news, but still believes those were isolated cases based on what he had learned about the school from a relative whose child went there.

Public outcry grows

Many internet users, however, have angrily rejected RYB's response as "inadequate" and calling for severe punishment for those found responsible.

Past incidents involving RYB kindergartens included two cases in northeastern China where four RYB teachers were each sentenced to more than two years in prison for abusing more than 20 children.

Amid growing public outcry over the scandal, Chinese government censors seem to have moved to contain the fallout. Many users have complained about the disappearance of their posts on the subject on social media. Comment sections are turned off for many online news reports on this story.

Across Chinese cyberspace, however, parents of young children have started sharing tips on detection and prevention of such cases -- some directly copied from school literature in the United States.

Earlier this month, videos of teachers at a Shanghai kindergarten physically attacking kids and force-feeding them what appeared to be mustard went viral.

Shanghai police quickly detained several employees at the facility, while the municipal government's women's affairs agency, with which the kindergarten is affiliated, had to apologize to the parents and public.

Critics have long said current Chinese laws are too vague and lax on child abuse and sexual molestation cases.

Media in China have documented a rising number of incidents of abuse at childcare facilities, often in small cities and towns. In a lengthy investigative piece published last year, the Xinhua news agency said only 968 cases of sexual abuse against children were recorded nationwide between 2013 and 2015, involving at least 1,790 children, with many remaining unreported.