Three children have now died in New York state from a possible complication from the coronavirus involving swollen blood vessels and heart problems, New York Gov. Andrew Cuomo said Saturday.

At least 73 children in New York have been diagnosed with symptoms similar to Kawasaki disease – a rare inflammatory condition in children – and toxic shock syndrome. Most of them are toddlers and elementary-age children.

Cuomo announced two more deaths a day after discussing the death of a 5-year-old boy Thursday at a New York City hospital. He did not give information about where the two other children died, or provide their ages. There is no proof that the virus causes the mysterious syndrome.

Cuomo said the children had tested positive for COVID-19 or the antibodies but did not show the common symptoms of the virus when they were hospitalized.

“This is the last thing that we need at this time, with all that is going on, with all the anxiety we have, now for parents to have to worry about whether or not their youngster was infected,” Cuomo said at his daily briefing.

New York is helping develop national criteria for identifying and responding to the syndrome at the request of the Centers for Disease Control, Cuomo said.

Children elsewhere in the U.S. have also been hospitalized with the condition, which was also seen in Europe.

At least 3,000 U.S. children are diagnosed with Kawasaki disease each year. It is most common in children younger than 6 and in boys.

Symptoms include prolonged fever, severe abdominal pain and trouble breathing.