ROCKY MOUNTAIN NATIONAL PARK, Colo. — Two wildfires burning in Rocky Mountain National Park could affect visitors’ plans during Labor Day weekend.

According to the park, the fires are called the Forest Canyon Fire and the Mirror Fire.

The Forest Canyon Fire is burning below Trail Ridge Road between the Rock Cut and Forest Canyon overlooks. It has burned about 5 acres.

Two single-engine air tankers dropped fire retardant in the area Friday morning.

However, the park said it was ineffective due to the steep terrain and valleys in which the fire is burning. A type-1 helicopter was expected to join the firefighting effort during the afternoon.

The Forest Canyon Fire is burning mostly lodgepole pine. Half of the trees had been killed by insect infestations. RMNP says the fire area has not burned in 800 years.

“Fire behavior is being driven by steep terrain and the amount of fuel,” a park spokesperson said.

The cause of the fire has not been determined. However, a thunderstorm with lightning moved through the area Thursday.

Trail Ridge Road remains open. Upper Beaver Meadows road is closed due to aviation operations.

The Mirror Fire is burning in a remote northern section of the park in spruce fir forest. The Mesa Verde National Park Helitack crew is assigned to the fire.

Mirror Lake Trail is closed from its junction with Mummy Pass Trail north to Mirror Lake. Comanche Peak Trail is closed between the park boundary south to Mirror Lake.

Mirror Lake and Koenig stock campsites are closed. Reservations for the back-country sites are cancelled until further notice.

In addition to the crew from Mesa Verde, personnel from the Estes Valley Fire Protection District, Grand Lake Fire Protection District, Boulder County Fire and the Arapaho Roosevelt National Forest are assisting in the firefighting effort.