UPDATED 03/10/11 11:36 a.m.
CHICAGO (CBS) -- Parents want answers about what happened inside a Chicago Public elementary school, a day after more than 30 children were sent to the hospital.
Officials said the children suffered from some kind of rash, but the exact cause was unclear.
On Thursday morning, more than a dozen parents gathered outside the school. They said they kept their children at home for their own safety.
Janelle Cirado, 12, was one of the students who was taken to the hospital.
"Terrified, terrified," said her mother, Mary Cirado. "She said, 'Mom, two women scrubbed me down. I was terrified.' She said it was itching and burning on her leg and on her arm. She had bumps on her arm and on her legs."
Hospital workers wore hazardous materials decontamination suits as they brought in children's backpacks and belongings, so as not to risk their own safety.
Mary Cirado said doctors told her daughter she had been exposed to a chemical substance.
"We were told that it was a chemical reaction to something. They really don't know what it is. They did tell me that she was scrubbed down, and we're here because we want the whole school scrubbed down," she said. "My daughters are not safe here. That's the reason why I didn't bring them today."
All the affected students had been in an art class, and the principal isolated the first-floor art room as a precaution.
School officials said the students were only using crayons, paper and other typical art class supplies, nothing that would be toxic.
Chicago Public Schools spokeswoman Monique Bond added that firefighters and hazmat teams said there was no indication of any type of toxic school or contamination, and there were no fumes detected.
A Fire Department spokesman said the students' symptoms were initially believed to be psychosomatic.
But another mother said her daughter's doctor pointed to construction fumes as a possible cause for the rash.
"So it makes her feel said because she felt her child was safe in the school," said Lisa Andino, who translated for the mother, Laura Cross.
CPS says there is no construction going on at the school.
The parents say they won't send their kids back to class until every room is cleaned – not just the auditorium and art room where the rashes were detected.
But CPS said in a statement Thursday that they did indeed clean the whole school before it opened for classes Thursday. Crisis management and safety staff are also at the school for the second day.
The American Red Cross is planning to cover the hospital bills that some of the families can't afford to pay.
for more features.