Two elk hunters who had been missing in the Colorado backcountry for a week were killed by lightning, the local coroner told Outside.

Conejos County Coroner Richard Martin confirmed to Outside that the 25-year-olds died after being struck by lightning while hunting in the Rio Grande National Forest, a vast backcountry area encompassing more than 1.8 million acres. Rescuers found the two men beneath a large tree, officials said.

Ian Stasko of Utah and Andrew Porter of North Carolina disappeared on September 11 after they “failed to check in with loved ones at a predetermined time” when bad weather swept through the area.

Martin told Outside that he believes lightning struck the tree the two were standing under and then traveled through the ground to make contact with them.

“It was not a direct strike to the body,” Martin told Outside.

“They were standing there talking and then they weren’t, that’s how fast it happened,” Martin added. “Electrical current stops all cardiac activity and all brain function immediately.”

Martin said that the event was “incredible and very unusual.” Roughly 40 million lightning strikes hit the ground in the U.S. every year, but the odds of being struck are less than one in a million, according to data published by the Centers for Disease Control and Prevention. One in ten lightning victims will die after being struck.

“Although lightning affects all regions in the United States, the Southeastern states are most at risk. Lightning generally decreases from the southeast to the northwest, except for a few places, such as the Rocky Mountains, where thunderstorms occur regularly during the summer,” writes the agency. “Florida, Texas, Colorado, North Carolina, Alabama, Arizona, Georgia, Missouri, New Jersey, and Pennsylvania have the most lightning deaths and injuries.”

Bridget Murphy, Porter’s fiancée, wrote in a Facebook post that he was an experienced outdoorsman “who was in the wrong spot at the wrong time.”

“It is OFFICIAL, that a lightning strike near them took them in an instant,” Murphy wrote. “They didn’t do anything wrong, they didn’t feel fear or pain. He was just trying to get back to the car as storms rolled in on Friday-September 12. It was out of everyone’s hands, and I am so grateful we found them so they can be at peace.”

After a weeklong search consisting of more than 50 search and rescue teams, both men were found deceased on September 18, Conni Ricci of the Conejos County Sheriff’s Department confirmed to Outside.

Conejos County Sheriff Garth Crowther told The Colorado Sun that when searchers found the men, both were dressed in camouflage clothing and had a single small shared daypack. They were located close together and had not set up camp. One had a bow, neither had a gun, and their emergency GPS beacon had not been activated, the publication reported. Outside also contacted the sheriff’s office for additional comment and will update this article accordingly.

At the time of their disappearance, the sheriff’s department said that “heavy rain and bad weather” had swept through the region. Martin added that lightning strikes were frequently recorded during the storm.

“While they are experienced hunters, bad cold storms and fog came in quickly and continuously until [September 14] morning. A lot of their gear is still in their car at the trailhead, as we assume they probably thought they were going out for a quick evening hunt with clear weather,” wrote Murphy in a September 17 Facebook post.

Lightning does not need to directly strike a person in order to kill them. When lightning strikes the ground, the National Weather Service writes that the electrical discharge “and along the ground surface (not deep into the ground). This creates a dangerous and potentially deadly ground current near the lightning strike.”

Most human lightning deaths in the U.S. are related to ground current.

The National Lightning Safety Council recommends that people monitor weather conditions when recreating in the backcountry and seek a safe place immediately if the sky appears threatening or thunder is heard.

The best way to prevent being struck by lightning is to avoid bad weather. In this educational series, Outside shares ways to keep you safe from lightning if you’re caught in a storm.