BANGKOK(AP) — Last month, an American man and his teenage son tragically passed away after being attacked by wasps while ziplining at an adventure camp in Laos. The incident, which resulted in them being stung multiple times, was confirmed by a hospital official on Thursday.

Dan Owen, who served as the director of an international school in nearby Vietnam, and his son Cooper, were targeted by the wasps on October 15th at Green Jungle Park. The attack occurred as they were descending from a zip line tree platform.

Situated outside Luang Prabang, a well-known tourist destination in Laos recognized as a UNESCO World Heritage Site in 1995, the camp is a popular attraction.

The victims were initially taken to a nearby clinic before being transferred to Luang Prabang Provincial Hospital. Jorvue Yianouchongteng, the emergency room physician who attended to them, described their condition upon arrival as critical.

“The son was unconscious and passed away after half an hour, while the father was conscious and passed away about three hours later,” he told The Associated Press. “We tried our best to save them but we couldn’t.”

The doctor said both had suffered from severe anaphylactic shock after being stung more than 100 times across their bodies, but that exact cause of death had not been determined.

The Asian giant hornet, known as the “murder hornet” due to its aggressive behavior toward other insects, is found in Laos but so are several other species of wasps. It was not clear which type had stung the two.

The local clinic where the two were first treated refused to comment and the Green Jungle Park did not respond to a query from the AP. The Laos Foreign Ministry also did not respond to a request for comment.

The U.S. State Department said it could confirm the deaths of two U.S. citizens in Luang Prabang but would not comment further “out of respect for the privacy of the family and loved ones.”

In a Facebook post, Owen’s employer, Quality Schools International, praised him as “touching countless lives” during 18 years with the chain, which operates 35 schools around the world. It said he had worked at five of its schools and was director of the QSI International School of Haiphong in Vietnam at the time of his death.

“He was deeply loved across our community and will be profoundly missed,” the school said. “Our sincere condolences go our to the Owen family and all who knew and loved them.”