Firefighters and Hazmat responders are at the entrance to the C&S Wholesale Grocers Inc. facility in Aberdeen Wednesday evening after an ammonia leak was contained. (David Anderson | Aegis staff / August 22, 2013)

Harford County emergency crews contained an ammonia leak at an Aberdeen distribution center Wednesday evening.

First responders were alerted around 4:49 p.m., Rich Gardiner, spokesman for the Harford County Fire and EMS Association, said via text message Wednesday night.

There was a report of a leak of anhydrous ammonia at the C&S Wholesale Grocers Inc. facility in the 1000 block of Route 159 (Old Philadelphia Road), according to the Fire and EMS Association's media page on Facebook.

Gardiner said there were no injuries, but people in the building were evacuated. According to Harford emergency officials, exposure to the chemical can cause respiratory and vision problems.

Gardiner said crew members closed a valve on a pipe to stop the leak, which he said came through a pipe flange.

Crews from the Harford County Hazmat Response Team and the Maryland Department of the Environment responded, as did the Aberdeen Fire Department and the Aberdeen Proving Ground Fire Department, according to Hazmat Chief Clarence Ross.

Old Philadelphia Road was closed near the facility, and Harford County Sheriff's deputies detoured traffic at Old Philadelphia and Perryman Road.

Emergency crews began leaving around 6:30 p.m., Gardiner said. Old Philadelphia Road reopened around the same time.

Operations quickly resumed at the C&S facility; staffers and security personnel directed tractor-trailers, which were mixed with through-traffic, along the two-lane road and into the facility gates.

In a follow-up report on the incident Thursday, Ross wrote that the ammonia is used to refrigerate food stored in the warehouse and the leak occurred in seals to a "king valve" in the line leading to the cooling units. Emergency crews equipped with self-contained breathing units shut off the line, he wrote.

In addition to no injuries being reported, Ross wrote there were no code violations. A contractor arrived to repair the leak around 7:30 p.m. The facility was closed for three hours, he wrote.

Anhydrous ammonia is a colorless, highly irritating gas with a sharp, suffocating odor, according to Richard Ayers Sr., Harford County's emergency manager. People will notice the pungent odor at levels ranging from 5 to 50 parts per million (ppm). Irritating effects generally begin at levels between 25 and 50 ppm. More serious effects generally will not occur until levels are greater than 100 ppm, Ayers wrote Thursday.

Symptoms to exposure include burning of the eyes, nose and throat after breathing even small amounts. With higher doses, coughing or choking may occur, Ayers said.

Exposure to high levels of anhydrous ammonia can cause death from a swollen throat or from chemical burns to the lungs, and eye exposure to concentrated gas or liquid can cause serious corneal burns or blindness, he explained, noting that the severity of symptoms depends on the degree of exposure.