(CNN) Vanuatu has imposed a state of emergency and evacuated thousands of residents after a volcano on Ambae island erupted, blanketing much of the surrounding area in thick ash.

The Manaro #volcano on #Vanuatu 's Ambae Island erupted today. Here's a view of the ash cloud in the South Pacific, from the #Himawari -8 satellite. pic.twitter.com/7NV5Ut9llY

Ambae, which sits in the northerly cluster of islands which make up the Pacific nation of Vanuatu, is the visible portion of the massive Manaro Voui volcano, one of the most active in the world.

The entirety of the island's population -- some 11,000 people -- was evacuated in September 2017 when the volcano began erupting . At that point, the alert level was raised to 4, the second highest on the scale. It's not clear how many people returned home in the months following the evacuation.

For the current eruption, the alert level has been raised to 3, indicating a "minor eruption," according to Vanuatu's Meteorology and Geo-Hazards Department.

"The local population from Ambae and from neighboring island can hear rumbling, volcanic explosions from volcano, smelt volcanic gases, see volcanic ash and gas plume and glows over the mountain at night," the department said on July 21.

A shot from a government-run camera on Ambae shows the sky almost completely obscured by falling ash.

On Thursday, residents on the island said the ash was falling from the volcano so thickly that it blocked out the sun, according to Radio NZ . Photos and webcam footage showed the landscape blanketed in thick gray ash.

The government has given a period of two months for the evacuation of what is expected to be most of Ambae's population, Radio NZ reported.

Some residents had begun to be evacuated Tuesday, according to the Vanuatu Red Cross, which said in a statement villages in multiple parts of the island were already uninhabitable due to the ash fall.

"We tried to travel to the south today but we have to turn back, because trees are falling, visibility is very very poor, we cannot see far more than 2 meters," Red Cross worker Augustin Garae said. "The situation is getting worse now in the south, people are now leaving their homes and move to evacuation centers in the east."