“No one was injured and there was no need for evacuation,” spokesman Ken Fields said in an e-mailed response to questions.

The exact amount of chlorine released – which Fields called “a small amount” – is under investigation. The cause was listed as “equipment failure."

The 10:41 p.m. incident was reported to environmental regulators and emergency response authorities, Fields said.

The 48-year-old plant recently completed a multiyear plan to phase out chlorine production and its use of mercury. The plant is being reconfigured for other purposes, including the distribution of caustic soda and manufacture of bleach.