HOUSTON -- Seven custodians were treated and released at a local hospital after they were sickened while cleaning a northeast Houston school, officials told KPRC Local 2 Saturday.

Mold was found in an annex building at Key Middle School on Thursday after two workers fell ill and were hospitalized.

Cleanup crews went to the school on Friday.

Houston Independent School District spokesman Terry Abbott said the custodians were not cleaning mold when the incident happened.

Seven of 15 custodians were sickened, but they were not the only ones.

"Even the principal herself broke out," custodian Fred Holloway said.

The principal and assistant principal left the school and appeared to be coughing and having trouble breathing. One of them reached for her inhaler.

The president of the union that represents school custodians said the building is not safe.

"You can actually smell the mold and smell some of the areas that they went in there and tried to clean up the area with Clorox," Houston Educational Support Personnel Union President Wretha Thomas said.

Abbott said fumes from the bleach made the custodians sick. They have all been treated and released from the hospital and cleared to return to work, Abbott said.

Abbott said the school district aggressively finds and cleans mold. He said the building would be cleaned and ready for students on Tuesday.

Thomas said she is not sure how safe the students will be.

"No kids are in that classroom, but they have kids in the classroom next to those sick rooms," she said.

Abbott said studies have not shown unusual amounts of mold in the building.

Three air conditioning units were stolen from the school during the summer. Abbott said those thefts hampered the district's ability to keep the building cool during the summer break.

Custodians said more should be done.

"People are getting sick and this is a serious matter," Holloway said. "This is nothing to play with because you're playing with people's lives."

Union representatives said they plan to rally in front of the school on Tuesday morning.