On June 9, 2009, a contractor from Energy Systems Analysts (ESA) was installing an industrial water heater at the ConAgra plant. The ESA worker attempted to purge the air out of a three-inch pipe meant to supply natural gas to the heater, using natural gas. As per ESA's typical practices, the worker vented the purged gases into the utility room, which was ventilated by a fan. Workers struggled to light the heater, so they continued to purge the line over a two-and-a-half-hour period. Plant personnel were aware of the indoor purging, and were using their sense of smell to detect odors to gauge possible gas buildups. Personnel who entered the utility room and some in the packing room noticed the smell of gas, but were not concerned by it. The gas concentration ultimately surpassed its
explosive limit and was ignited at about 11:25 am. The explosion damaged of the facility, concentrated in the southern part of the plant where packing operations were conducted, and triggered a leak from the plant's refrigeration system, causing the release of about of
ammonia. Plant workers were brought to the Garner Senior Center to regroup. Search and rescue teams entered the building to locate possible survivors in the evening after the fires were extinguished. In all, three workers were crushed and killed, while 71 people were hospitalized with injuries, including three firefighters who had been exposed to ammonia. One worker succumbed to his injuries several months after the explosion. == Aftermath ==