Nathan Matthews, 43, died Friday from burn injuries sustained during a June wildfire burnover near the Colorado-Utah border, making him the fourth firefighter to die from the incident, the Wail confirmed.

Matthews had been hospitalized since the burnover enveloped his crew approximately one month ago. Three other firefighters died in the weeks following the initial incident.

A burnover occurs when a fire overruns a crew's position, cutting off escape and exposing personnel directly to the flame front. Such events are among the most lethal hazards in wildland firefighting.

The four deaths constitute one of the worst single-incident crew losses in Colorado wildfire history. State and federal investigators are examining the conditions that led to the burnover, including weather shifts, terrain, and crew positioning at the time.

No timeline for a formal report has been announced. Next-of-kin notifications for Matthews were completed Friday, according to sources familiar with the matter.

Investigators are expected to release preliminary findings in the coming weeks.