Staples High School was evacuated around lunchtime Wednesday as a precaution after the chemical substance freon leaked during work on the air-conditioning system.

The leak was discovered while work was being done on a cooling tower for an air-conditioning unit, according to First Selectman Jim Marpe.

He said there were "high levels" of freon detected in the boiler room where the air-conditioning system is located. He said the leak was confined to that room, and that it later needed to be ventilated.

Freon is an agent commonly used in air conditioning and other refrigeration equipment.

He said the school was evacuated as a precaution when the leak was discovered. "The workers notified the Fire Department, then pulled the fire alarm at the school," Marpe said.

That was just around noontime.

In an account on the incident emailed to parents of Staples students, Principal John Dodig reported: "Fire and police personnel arrived on the scene at once along with specialists in handling hazardous material.

"Students were very well behaved for the 1 1/2 hours we spent outside. Before we were allowed back into the building, fire personnel walked throughout the building taking readings. Only when the readings showed no freon present in the air did they let us back in," Dodig said.

There were no injuries reported, according to Marpe, and no students were exposed to the gas.