The Okmok Caldera volcano has erupted on an island, in Anchorage, Alaska. The volcano announced no warning before its eruption. After that, it sent an ash cloud of almost 50,000 feet high, said the geophysicist Steve McNutt.

The volcano erupted last Saturday morning, but the seismologists at the Alaska Volcano Center didn’t detect more than a series of small tremors hours before.

Okmok Caldera is situated 60 miles west of the fishing port of Dutch Harbor on one of Alaska’s Aleutian Islands, Unalaska Island, that has almost 4,300 full-time residents and 900 miles southwest of Anchorage.

The last eruption of the volcano happened in 1997 and spread ash clouds and lava that traveled five miles across the volcano’s caldera floor. Steve McNutt said that Okmok Caldera has shown signs of increased activity during the last few months.

The volcano rises to 3,520 feet and it’s a highly active one, with nearly 16 eruptions which occurred every 10 to 20 years since 1805.

The eruption on Saturday evacuated 10 people who live on the eastern side of the island. The residents located close to the volcano called the U.S. Coast Guard seeking evacuation. A fishing vessel took them to Unalaska.

Nine people, including three children were on the island, at fort Glenn, the cattle ranch near the Okmok Caldera. They called for help on a satellite telephone before losing the connection.