NASHVILLE, Tenn. (WKRN) — Several days after a concourse at Nashville International Airport (BNA) was evacuated amid reports of “noxious fumes,” airport officials shared more information about the irritant’s source, as well as the response timeline for the incident.

BNA said the initial calls about “an unpleasant odor” in Concourse C near Tootsies came in just before 2:45 p.m. on Sunday, April 16, so passengers and employees were evacuated from the concourse by Airport Operations and Department of Public Safety (DPS).

By 2:55 p.m., members of the Nashville Fire Department were dispatched to the airport to respond to “something airborne causing breathing problems,” according to officials.

BNA reportedly activated its Emergency Operations Center at 3:11 p.m. to help track down the location of the odor.

Photos and videos shared with News 2 showed emergency responders gathering on the tarmac outside the concourse, as well as walking through the airport with masks and oxygen tanks.

According to BNA, the fire department conducted air quality testing, found no hazardous contaminants in the air, and determined it was safe for people to return to Concourse C shortly before 4 p.m.

Then, at 4:10 p.m., officials said DPS reported a brown liquid sprayed onto the dust wall at the trash across from InMotion at the start of the concourse. However, passengers were still allowed to go back to Concourse C a few minutes later.

BNA announced at 4:35 p.m. the FAA issued a ground stop to help the airport return to normal operations safely, but that ground stop was lifted by 4:50 p.m.

In a statement released later Sunday evening, the airport said the fire department also took chemical samples, which revealed the substance involved in the incident was Butoxyethyl Acetate, a solvent commonly used in lacquers, varnishes, enamels, and resins.

However, on Wednesday, April 19, BNA reported that DPS determined the source of the irritant was actually bear spray.

A passenger had reportedly realized bear spray was in their backpack after leaving the Transportation Security Administration (TSA) checkpoint, so they tossed it in a trash can before boarding their plane.

Officials said video footage showed a custodian going through the trash, discovering the bear spray, and accidentally activating the canister.

“Nashville International Airport is committed to the safety of its passengers, staff, and airline partners. We take these maters seriously,” BNA said Wednesday. “Research was a critical component of this incident to understand the full scale of the situation to keep the public informed – as details unfolded. We will continue our efforts to provide an optimal experience for all travelers.”

Meanwhile, TSA released the following statement about Sunday’s incident:

TSA officials at Nashville International Airport were made aware of noxious fumes that were the cause of a temporary evacuation of Concourse C on Sunday, April 16. After initiating an internal investigation and discussing with BNA, we learned on April 17 that the item was bear spray missed during the security screening of a passenger’s carry-on bag and was later disposed of by the passenger in a concourse trash bin. TSA takes its role in transportation security and this situation very seriously and is continuing to review details with our airport partners to ensure appropriate corrective actions are taken.