A 7-year-old boy from Westchester County is among three young New Yorkers who have died from an illness believed to be linked to COVID-19, according to Gov. Andrew Cuomo's office.

It's called pediatric multi-symptom inflammatory syndrome. Doctors describe it as a toxic shock-type disease, and they say some of the symptoms include a rash, red tongue, lips or eyes, swollen hands and feet, and a fever and vomiting.

Gov. Cuomo says there are at least 73 cases of the illness and three deaths in New York. The deaths include a teen in Suffolk County, a 5-year-old boy in New York City, and the  7-year-old boy in Westchester County, according to the governor's office.

The child from Westchester died at Maria Fareri Children's Hospital in Valhalla.

Officials say at least a dozen children have been treated for the mysterious condition at Cohen Children's Medical Center in New Hyde Park on Long Island.

Cuomo said that at the request of the CDC, the state is helping to develop the national criteria for identifying and responding to COVID-related illness. The state Department of Health is also partnering with the NY Genome Center and Rockefeller University to conduct a genome and RNA sequencing study to better understand COVID-related illnesses in children and the possible genetic basis of this syndrome.

Experts say the condition appears to be a post-viral reaction to COVID-19. They say the cases appear in young people who have tested positive for the virus or who have COVID-19 antibodies, indicating they have previously been exposed to the virus.

"We now have a new issue that has come up in the fight against COVID-19 that is truly disturbing and it impacts our youngest New Yorkers," Gov. Cuomo said in a statement.  "This is a frightening new development, but rest assured we are doing everything we can to learn more and keep parents informed."

Doctors also stress that this condition is extremely rare, and most kids infected with coronavirus will be fine. If a child suddenly develops a sunburn-like rash, their parents should seek medical help immediately.