Salmonella found in omelette served to children at the Rostov- on-Don kindergarten had caused mass food poisoning, Head doctor of the local municipal hospital Vitaly Zhdanov told Tass on Monday.

Laboratory tests showed the presence of salmonella that caused mass intestine poisoning, he said. It was established that only the children who ate the omelette fell ill, while the children who ignored the omelette were not infected.

Thirty-three children and four grown-ups from the kindergarten personnel remained at the Rostov Clinical Hospital by Monday afternoon. Three children were allowed to leave the hospital, but they are undergoing outpatient treatment.

The children are in a condition of medium seriousness, and their life is not in danger, the hospital personnel said. Doctors said it might take five- six days to complete hospital treatment. The Rostov-on-Don district prosecutor’s office has opened a criminal case. Victims have filed for medical assistance.