Tulsa's Dove Science Academy has canceled classes because of mold.

School officials say it started from a plumbing leak, but some teachers aren't buying that.

Teachers, who don't want to be identified, tipped off News On 6 to the problem and said they have been sickened by exposure to black mold.

Fans blast through the halls of the school as restoration crews de-mold the 40-year-old building near East Second Street and South Memorial Drive.

"We had some flooding, so we called in people to inspect for mold on Friday," assistant principal John Franklin said.

Multiple teachers said they've are breaking out in hives and having trouble breathing.

They're blaming it on the mold, and say the school waited too long to try to fix the problem.

"We got the report on Friday and we started repairs on Friday," Franklin said. "They said we didn't have to close the school down, so we didn't until they were going to open up the walls."

Franklin said a plumbing issue caused water damage to two restrooms, a hallway and part of the cafeteria.

An expert said there's one key component that makes mold conditions worse.

"For mold to colonize and grow, it needs to have water," Liberty Occupational Health Management President Rob Thompson said.

Although the plumbing leak happened on Friday, Franklin admits it may not have been the original cause of the mold.

"I think it predates that," he said.

Thompson said it's best to treat mold as soon as it's discovered.

"We don't usually hear about the problem until it gets a little beyond normal," Thompson said. "You try to find out where the source and the origin of the problem is. You fix that, then you can tackle any mold problem that might be present, like remove carpeting, remove wall board, those kinds of things."

Thompson said mold can either have a toxic or allergenic effect on people who are around it.

"We have allergic reaction, which is sneezing, itchy eyes, runny nose, maybe a sore throat or those kinds of things," he said.

School leaders are waiting on a final air quality report before classes resume.

As many as nine teachers at the academy are reportedly out sick.

The school will not confirm that, but Franklin said quite a few kids have been home sick from flu-related illnesses.