LOS ANGELES - Los Angeles County announced that four children who tested positive for COVID-19 had been diagnosed with a mysterious inflammatory condition since March 1, with 21 more suspected cases to be identified.

Three of the four kids, aged 8 months to 2 years old, had been discharged from hospital and another one was being treated in critical condition, the county's Public Health Director Barbara Ferrer disclosed at a daily briefing.

The 21 suspected cases were waiting for results of their coronavirus antibody testing.

In New York, dozens of potential cases and three related deaths of kids have been reported, local ABC 7 news channel reported.

Doctors from Children's Hospital Los Angeles speculated that the mysterious illness could be a delayed response by the children's body to COVID-19, it said.

The illness reportedly turned a child's immune system against its blood vessels.

World Health Organization Director-General Tedros Adhanom Ghebreyesus said on Friday at a virtual press conference that Multisystem Inflammatory Syndrome in Children may be related to COVID-19.

He told reporters that in the past weeks, reports from Europe and North America have described a small number of children being admitted to intensive care units with a multisystem inflammatory condition with some features similar to Kawasaki disease and toxic shock syndrome.

Kawasaki symptoms include persistent high fever, rash, red cracked lips, red tongue, swollen eyes, hands and feet, and enlarged lymph nodes in the neck.