A third attendee at the Burning Man festival has died while being transported to a hospital, officials confirmed, adding to the growing number of fatalities at the event's 40th anniversary.

The unidentified individual was en route to a hospital in Reno, approximately 120 miles from the festival grounds in the Black Rock Desert, when they died. The cause of this latest death remains unclear.

This incident follows the discovery of two other deceased men on the festival campgrounds last week. Jerry Allen, Pershing County sheriff and coroner, stated that while the festival typically averages one death per year, there have been two within the festival confines and a third in transit to Reno this year. "I have received information regarding a third who died in transit to a hospital in Reno," Allen told NBC News in a statement.

The identities of the previously deceased individuals were reported as Craigh Mann, 60, and Sampson Tshombe.