Food poisoning at a kindergarten in northern China sent 76 students and teachers to the hospital on Monday, according to official Chinese media.

The students and teachers in Elfin Kindergarten in Baotou City started to show symptoms late last week and were diagnosed with “contagious dysenteric viruses.” All are receiving treatment at a local hospital, reported state media.

Elfin Kindergarten is a private school that has more than 400 students and teachers. Over 280 children dined at the kindergarten during the suspected food poisoning incident, which local health authorities are still investigating.

The incident will likely add to growing concern in China over the safety of the nation’s food supply. 

After last year’s highly publicized melamine-tainted milk powder scandal, which sickened over 300,000 and killed six infants, Beijing passed a series of food safety laws to increase governmental oversight, but it is unclear whether tougher laws will results in dramatically safer food.

The outbreak also comes after China postponed its 3rd annual international food safety conference on short notice to celebrate the 60th anniversary of the revolution. The conference has been rescheduled for early November.