By Yereth Rose

ANCHORAGE (Reuters) – Residents of Anchorage, Alaska’s suburb were told to evacuate a mountainous region after an avalanche buried a roadway and caused another slide.

Anchorage Mayor Dave Bronson issued an evacuation order citing “a grave, immediate threat to health, safety and welfare of citizens” in Eagle River on the city’s outskirts.

Shortly before midnight GMT (0800 GMT), an avalanche burst down from a mountainside, covering the main road with snow layers up to 80ft (24m) thick. Local officials stated that only half the snow from the unstable slide area was removed at the time. A secondary avalanche, however, is possible.

Uncontrolled releases at unspecified times could lead to the death of innocent people. Anchorage Municipal Manager Amy Demboski stated that they want to stop it at every opportunity.

Demboski explained that access was cut to around 100 homes by the avalanche, which left some without power.

Demboski explained that evacuations of residents in affected areas and mitigation measures such as placing explosives via helicopter to control an avalanche will make the area more safe over the following days.

Alex Boyd (Assistant Anchorage Fire Chief) said that the emergency crew has made a trail to help those who are stranded and is operating snowmobile shuttles.

Bronson’s spokesman Corey Allen Young said that no injuries were reported. Officials are assessing damage to the houses.

Officials said that although avalanches can be common in the Chugach Mountains region, this event is unprecedented due to its size and location.

This avalanche was massive in size. It has been described by avalanche experts as a once-in-a-hundred-year event,” Demboski said at the news conference.

Demboski warned that the snow could block the roadway in the affected area until the end of the season if the mitigation is not done.