ROCKFORD, Ill. (WTVO) — A fire started in a test lab chamber at NTS on South Central Avenue on Thursday, forcing the business’ closure for the night.

The Rockford Fire Department said the flames were contained to the chamber and were extinguished within 10 minutes of their arrival.

Smoke still filled the facility and took some time to ventilate.

Two employees were medically evaluated by paramedics at the scene.

The remainder of the employees were sent home for the night.

The damage was estimated at $500,000 and investigators are working to determine the cause of the fire.

NTS does electromagnetic energy testing for electronic devices, to test device interference and compatibility for aerospace, defense, and commercial programs.