HOUSTON -- Two teachers became sick at a northeast Houston middle school Monday morning and were taken by ambulance to the hospital where they were treated and released, KPRC Local 2, Your Education Station, reported.

The incident happened at Francis Scott Key Middle School, 4000 Kelley, which was inspected earlier this month for dangerous levels of mold after nine janitors got sick.

The teachers said they vomited, had difficulty breathing and had watery eyes shortly after settling into their classrooms.

"They walked in the building this morning -- nauseous and started vomiting, so they were immediately transferred," said Corina Ortiz, a union steward.

The teachers' union said it believes the school has an air-quality problem or mold.

"There's nothing wrong that maybe they found. But there's obviously something very wrong in this building or my members wouldn't be keeling over," said Gayle Fallon with the Houston Federation of Teachers. "Why are people getting sick?"

A city inspector agreed with Houston Independent School District inspectors that the school did not have dangerous or unusual levels of mold. Officials said the janitors became ill from cleaning with bleach.

The teachers were in the school's main building. The complaints about mold happened in the school's annex building.

Parents just want the problem fixed.

"That's a big concern because I did not know that they're saying they don't really know what it is. If it's not mold, then what is it?" parent Katrina Ivory said.

"I tell my kids every day -- if they feel sick or anything, please call me, by all means," parent Tosha Moore said.

The teachers were released from the hospital Monday afternoon.

HISD officials said they would not comment until they know exactly what made the teachers sick.

Officials said the air conditioner was shut down over the weekend for cleaning and was not turned back on until Monday morning. So the inside of the building was extremely hot and humid.

Union officials said they have received 18 workmen's compensation claims from the school -- nine of them from the custodians who were overcome by bleach fumes.