Officials have yet to release the name of the firefighter, while they contact next of kin.
Firefighters have been battling nearly 50 small blazes in Jackson and Josephine counties, caused by lightning strikes on Wednesday night.
Earlier this month, firefighter Colin Hagan was also killed after being struck by a tree while working at the Big Swamp fire near Oakridge.
This Josephine County fatality will be the sixth wildland firefighter killed nationally this year, according to the U.S. Fire Administration. On a separate fire in Jackson county on Thursday, a firefighter had to be removed from the line and treated for a heat-related illness.
ODF officials say their teams will be taking time to discuss these incidents and ensure firefighters are prioritizing safety when out in the field.
Teams in both counties have made significant progress in containing the recent wildfires. Out of the 48 fires confirmed, 17 have been fully extinguished and the remaining 31 are being lined and mopped up. No homes have been threatened and no evacuation orders are in place.