(Beijing) — President Xi Jinping ordered Chinese authorities on Monday to launch a thorough investigation into a vaccine manufacturer’s sale of over a quarter-million substandard vaccines for diphtheria, pertussis and tetanus (DPT), and to punish those responsible.

The breaching of laws and regulations in the manufacturing of the vaccine by Changchun Changsheng Life Sciences Ltd. is “abominable” and “shocking,” and authorities must respond to public concerns in a timely manner, the official Xinhua News Agency quoted Xi as saying.

Also on Monday, police in Changchun, Jilin province, where the company is based, announced that they have arrested four company executives, including Chairwoman Gao Junfang.

The news comes just days after Changchun Changsheng was ordered to stop making its rabies vaccine after it was found to have tampered with production data. The latest scandal has provoked an outcry among Chinese parents and sent authorities scrambling to contain the situation.

Over 250,000 doses of the DPT vaccine were found to be substandard. Most were sold in Shandong province, the Jilin Food and Drug Administration said in a statement on Friday.

China has been plagued by vaccine scandals in recent years. Another company, Wuhan Institute of Biological Products Co. Ltd., sold more than 400,000 doses of substandard DPT vaccines, the China Food and Drug Administration (CFDA) said in November.

In 2013, 17 children died after they were given a hepatitis B vaccine produced by Shenzhen Kangtai Biological Products Co. Ltd., though no link was found between the deaths and the vaccine, according to a joint investigation by the CFDA and the National Health and Family Planning Commission. But investigators said the vaccine could have led to “abnormal reactions” among recipients.

As parents rushed to find out if their children had been exposed to Changchun Changsheng’s vaccines, regulators struggled to contain the damage. In one case, a government-run news outlet, lznews.cn, was forced to apologize after it falsely claimed that none of the substandard products had been sold in the city of Zibo, citing the local food and drug authority.

The apology came after parents in Zibo published documents online showing that their children had been administered with the batch of the DPT vaccines in question.

Substandard vaccines from Changchun Changsheng have been administered to more than 210,000 children in eight cities in Shandong, including the provincial capital of Jinan, and in Zibo, according to the Shandong Center for Disease Control and Prevention.

No children exposed to the substandard products have been sickened by them, and they will be given new immunizations, the center said Monday.

Premier Li Keqiang said such violations have broken a “basic moral threshold,” and those responsible will be punished.

The CFDA said it will begin unscheduled inspections at all vaccine manufacturers in China while it looks into violations at Changchun Changsheng.