Plano ISD School Closing?

In the news they're taking about the Plano IDS school closing. They say the students at Plano Sigler Elementary School have been evacuated to Vines High School due to a "noxious smell," according to a Plano Independent School District spokeswoman.
What's that smell about?

Nobody know where the smell comes from, they closed the school just to be careful.
It's ok, people can get sick if the smell comes from something dangerous.

The district's facility and security departments are investigating the source of the odor. Plano ISD has evacuated students from Sigler Elementary School this morning to Vines High School because people complained of an odor in the school.

Plano EMS battalion chief Marty Wade just told me that a hazardous materials team is on its way to Sigler Elementary School to take readings to try to find out the source of the odor.

Plano ISD facilities and safety and security staff responded and implemented the appropriate relocation plan while this situation was being addressed.

The fire department did not take part in the evacuation. The were no reported injuries or illnesses of students or staff.