Tacoma fire officials said workers were drying off the roof with a gas-powered leaf blower prior to painting and fumes likely got into a nearby intake vent.
"Teachers and staff and students reporting feeling light headed, nausea, and sickness," said Joe Meinecke with Tacoma Fire. "So we upgraded this to a mass casualty incident to bring in enough resources."
The school was evacuated and and 47 staff members and students were taken to local hospitals as a precaution for treatment of respiratory complaints, nausea and dizziness. They were all expected to be OK.
"There were no serious injuries to report," Meinecke said. "I'm a parent myself and I know this would be stressful news to get a big incident at school."
As word spread of the incident, parents flocked to the school to check on their kids.
"Some of the kids had gone to the hospital and we had to come check in," said Morrigan Oran, parent of a 6-year-old first grader. "I just kind of freaked out and came down here. I didn't have time to think about it honestly."
Felisha Singleton, whose son is in 4th grade, said her heart just dropped when she heard the news, but was relieved to find that her child was still there.
"It was a blessing" she said. "I don't mind waiting, because I know my baby's in there, but it's still scary because if something's still going on, should the kids still be in there?"
Firefighters cleared the building and gave the all clear just before noon, and classes resumed.