A short time earlier, a package containing two canisters of the liquid cryogenic, Tetrafluorethane, arrived at Dr. Lisa Sherman's third-floor dermatology office.
Dermatologists use the product to freeze off warts and moles.
The package had been crushed and a canister damaged, Warrenton Volunteer Fire Department Chief Kevin Swain said. Seven people were exposed to the chemical, the chief said. All received treatment at Fauquier Hospital and were released.