Students returned to a school Tuesday where seven custodians were sickened while cleaning with bleach, KPRC Local 2 reported.

A Key Middle School science teacher reported for duty but said he had to leave the building within minutes of getting to work.

"It's very scary to go to the place that you've worked the last 11 years, and you've never have a reaction, and then go in and have these type of reactions," Ronald Jacobs said. "It's very, very scary."

Jacobs said something in the air made him feel ill.

Houston Independent School District spokesman Terry Abbott said there is no mold at the school. The city of Houston's health department and environmental and mold experts have examined the school and found no evidence of unusual levels of mold.

One grandparent said the test results made her feel comfortable sending her granddaughter to school.

"With this being a good school in the Kashmere Gardens area, it will surely be taken care of pretty fast," Carolyn Harris said.

Seven janitors fell ill while trying to clean the school over the holiday break.

Some workers raised concerns about mold in the school and took pictures, but school district officials said the pictures were old.

Abbott said bleach fumes caused the janitors' illnesses.

KPRC Local 2's cameras were allowed into the school on Monday. Our crew did not see any mold.

"It's time to stop the scare tactics," Abbott said. "Stop trying to scare kids. This building is fine."

Teacher's union representatives said they will not drop the mold issue until people stop complaining.

"Walking in the door they were having some kind of reaction," Houston Federation of Teachers representative Corina Ortiz said. "Watery eyes, scratchy throats. It continues."

Crews have changed the air filters at the school.

The school district plans to monitor the air at the school for several days.