A carbon monoxide incident at a campsite in Giswil, Switzerland, led to 26 people suffering from poisoning, with 17 requiring hospitalization.

The event occurred during a dinner in a dome tent on Saturday evening, where attendees suddenly experienced unconsciousness or discomfort around 10:30 PM.

Initial investigations suggest a high concentration of carbon monoxide accumulated in the tent, though the exact cause remains under investigation by the Obwalden Cantonal Police and the Forensic Institute Zurich.

The incident prompted a large-scale emergency response, involving rescue services from seven cantons, two rescue helicopters, and multiple police patrols.

The source of the carbon monoxide, possibly linked to a heating system, is yet to be confirmed.