HUMMELS WHARF, SNYDER COUNTY (WBRE/WYOU) — After an ammonia leak at National Beef Packing Company in Hummels Wharf, employees were evacuated and residents were told to stay inside.

Hummels Wharf Fire was sent to the National Beef plant around 8:00 p.m. on Friday for a “hazardous materials situation.” However, upon arrival the incident was upgraded to an outside hazmat situation.

Hummels Wharf Fire said it was, “evident that the anhydrous ammonia was spread throughout the area surrounding the facility.” The fire company did upgrade the incident one more time to a mass casualty incident after 46 staff and contractors were exposed to the leak.

Originally it was believed that 3,000 pounds of ammonia leaked but officials later determined that it was only 1,800 pounds.

“The leak was due to a valve failure while the facility was transferring the Anhydrous Ammonia from their on-site tanks, to trailers, so they could perform needed upgrades and repairs to the facility. The Anhydrous Ammonia is used for refrigeration at the facility,” said the Hummels Wharf Fire-Rescue in a Facebook post.

Just before 10:30, residents were advised to close windows and doors and turn off ventilation equipment (A/C, fans) that draw outside air.

Members of Station 70 worked on scene for six hours. Only one patient was transported to a local hospital.