On Wednesday, 24 Amazon employees working in a Robbinsville Township, New Jersey, warehouse were sent to five different area hospitals after a 9oz canister of bear spray was deployed.

Early reports that the canister was punctured by an Amazon robot have not been confirmed by either Amazon or the Township's communication official, John Nalbone. Nalbone told Ars that Robbinsville first responders only reported that an "automated machine" was to blame, which could mean anything from a programmed robotic arm to an automated conveyor belt. (Of course, may readers of Ars would agree that defining the meaning of "robot" is more than just an exercise in trivia. This Wired article explores the topic more deeply.)

On Wednesday evening, one of the 24 people hospitalized was in critical condition, while another 30 were treated on the scene, ABC News says.

In a statement to Ars on Thursday morning, Amazon external communications regional manager Rachael Lighty said:

Wednesday at our Robbinsville fulfillment center, a damaged aerosol can dispensed strong fumes in a contained area of the facility. The safety of our employees is always our top priority, and a full investigation is already underway. All employees in that area were relocated to a safe place, and employees experiencing symptoms were treated onsite. As a precaution, some employees were transported to local hospitals for evaluation and treatment. All of the impacted employees have been or are expected to be released from the hospital within the next 24 hours. We'd like to thank all of the first responders who helped with this incident.

All the Amazon employees were covered by employer-provided healthcare, Lighty added. Amazon employees are not unionized, ABC News reported, adding that "the fumes were confined to the fulfillment center's third floor south wing."

Self-defense blogs seem to agree that bear spray is less incapacitating than pepper spray made to be used against humans, but it is still quite irritating. The BBC reports that, according to the "Get Bear Smart Society," bear spray causes "a nearly total, yet temporary, loss of sight and severe restriction of breathing" in humans.

Worker safety in the presence of automation is an old story, and automation is generally a boon to worker safety. But while incidents may become more rare, they can be gruesome when they happen. For example, in 2015, a man was killed by a robot in a Volkswagen factory.