No deaths or injuries have been reported.
The eruption, the first on the Canary Islands in 50 years, sent lava and smoke spewing into the air as the lava flowed toward the sea.
In the hours before the eruption, a large increase in seismic activity around the volcano was reported.
“It was horrible,” a 53-year-old tourist from Austria by the name of Eva told Reuters. “We felt the earthquake; it started in the morning … Then at three in the afternoon the lady from our house came and said you have to pack everything and leave quickly.”
“We’re happy to go home now,” she said at the airport, before boarding a flight to Austria.
Authorities say the eruption would likely continue for several days.
Given the uncertainty about which direction the lava will flow, people with mobility issues have been evacuated from several coastal towns.
Airspace around the Canaries remains open.
Spanish Prime Minister Pedro Sanchez cancelled his trip to the United Nations General Assembly in New York and instead visited the affected area Monday.
Some information in this report comes from Reuters.