BOISE, Idaho (AP) — Federal officials say a heart attack is to blame for the death of a wildland firefighter who passed away this summer after completing a physical training exercise.

Officials with the U.S. Bureau of Land Management say 33-year-old Terry Sonner from Hammett collapsed after completing a 2-mile training run in June. According to the agency's final investigative report in early November, Sonner's last physical examination was in 2014. He had also cleared both a health questionnaire and physical test earlier this year.

Sonner had been a BLM firefighter for 14 years. He had been recently promoted to superintendent. Heart attacks and other medical issues have claimed six out of the 13 wildland firefighter deaths this year — making it the top cause of death for the second year in a row.