A total of 54 Amazon workers in New Jersey suffered the effects of being exposed to bear repellent spray yesterday while at work in one of Amazon's warehouses. Thirty of the workers were treated at the scene, 24 needed to go to hospital, and one remains in a critical condition. The incident was caused by a robot.

As ABC News reports, one of Amazon's many automated robots managed to puncture a nine ounce can of bear repellent spray. In doing so, a concentrated form of Capsaican was released into the air and nearby workers were exposed to it. Capsaican is an active component of chilli peppers and therefore forms a very effective irritant for both bears and humans. You won't be surprised to hear it's also a major ingredient in pepper spray.

According to an Amazon spokeswoman, the repellent was released in a "contained area of the facility" which was subsequently filled with strong fumes. The employees transported to five local hospitals were done so just as a precaution and Amazon believes they are all expected to be released within 24 hours.

The area where the incident happened is on the third floor of the warehouse's south wing. The ventilation system would have cleared the fumes away fairly quickly, but not before workers near to the can had been exposed to strong fumes. Due to the time of year, you can imagine how busy the warehouse must be trying to fulfill all the extra orders for the holidays, especially with Amazon's 12 Days of Deals promotion currently underway.

The Retail, Wholesale and Department Store Union is not happy, though. Union president Stuart Appelbaum released a statement saying, "Amazon's automated robots put humans in life-threatening danger today, the effects of which could be catastrophic and the long-term effects for 80 plus workers are unknown." It's unclear why he references over 80 workers when only 54 are known to have been treated at this time.

This article originally appeared on PCMag.com.