BANGKOK — An American man and his teenage son died last month after they were swarmed by wasps while ziplining at an adventure camp in Laos and stung many dozens of times, a hospital official said Thursday.

Dan Owen, the director of an international school in neighboring Vietnam, and his son Cooper were attacked by the insects on Oct. 15 at the Green Jungle Park, as they were descending from a tree at the end of the zip line.

The camp is located outside the city of Luang Prabang, a popular tourist site in the Southeast Asian nation that was named a UNESCO World Heritage Site in 1995.

The two were taken to a local clinic and then transported to Luang Prabang Provincial Hospital where they arrived in critical condition, said Jorvue Yianouchongteng, the emergency room physician who received them.

“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.”