By Helen Regan, Isaac Yee, Masrur Jamaluddin, CNN

(CNN) — A volcanic eruption killed three people and triggered a rescue operation to get more than a dozen hikers stranded near the crater of Indonesia’s Mount Dukono to safety on Friday morning, officials said.

Singapore nationals and an Indonesian citizen were among those killed when the volcano, on the island of Halmahera in North Maluku province, erupted, according to the island’s police chief and search and rescue officials.

Nine foreigners and 11 local hikers were climbing Mount Dukono at the time of the eruption, North Halmahera Police Chief Erlichson Pasaribu told Indonesia’s Kompas TV.

Seventeen of the 20 climbers have been safely evacuated, Iwan Ramdani, head of the Ternate Search and Rescue (SAR) Office, said at 6 p.m. local time. The bodies of the three deceased currently remain on the mountain. Search operations have been suspended for Friday and will resume on Saturday.

A huge column of smoke and ash could be seen rising above the mountain in dramatic video from near the crater recorded by Alex Djangu, an Indonesian mountain guide.

Djangu was guiding two German tourists on Mount Dukono when he felt deep tremors before the eruption, telling CNN it was “very scary.”

Djangu said they heard sounds coming from below the crater at around 3 p.m. local time Thursday. He then flew a drone to inspect the crater conditions from the air.

“The observations showed the crater was filled with volcanic material, which was not normal. Then we heard two explosions,” he said.

Shortly afterwards, he noticed another group of hikers making their way to the crater’s rim. “When the major eruption occurred at 7:41 a.m. on Friday, it seemed the group had just arrived at the summit and were enjoying themselves,” he said.

“I saw the small rocks and gravel sliding down because of the tremors, then I told my clients we have to run down,” he said.

While Djangu and his group were able to safely evacuate, he said many hikers remained at the crater at the time of the eruption.

“When we were about 100 meters (328 feet) away, I saw two groups of local tourists, one group of nine people already close to the rim and the other were videoing for content.”

“I hope they are still alive,” he can be heard saying in the video.

The volcano, he said, is highly active and continued to erupt into Friday afternoon “with supersonic sound.”

Noting the lack of climbing restrictions in place, Djangu said, “At Dukono there is no security post controlling entry or exit routes, and of course there are no forest police preventing people from climbing.”

In an update Friday evening local time, Indonesia’s disaster agency urged tourists and locals not to carry out activities on Mount Dukono while volcanic activity remained elevated, adding that people should always follow instructions from local authorities and the Center for Volcanology and Geological Hazard Mitigation (PVMBG).

Mount Dukono is one of Indonesia’s most active volcanoes, with authorities noting increased activity since late March.

Since December 2024, tourists and other climbers have been advised by the PVMBG not to take part in activities within a 4-kilometer (2.5-mile) radius of Mount Dukono’s epicenter. According to the organization, Dukono had seen a significant increase in explosive magmatic eruptions since March this year.

“When Mount Dukono does not erupt for several days, people need to be careful because it may be building up very high pressure. And that is what happened today,” Djangu said in the video.

Rescue teams could be seen on the mountain on Friday, and carrying at least one injured person on a stretcher through the forest, in photos from Indonesia’s national search and rescue agency BASARNAS.

In a statement sent to CNN, the Singapore Ministry of Foreign Affairs said it was working closely with Indonesian authorities to provide consular assistance and support to affected Singaporeans and their families.

Indonesia sits on the “Ring of Fire,” a band around the Pacific Ocean where earthquakes and volcanic activity frequently occur. One of the most seismically active zones on the planet, it stretches from Japan and Indonesia on one side of the Pacific to California and South America on the other.

This is a developing story and will be updated.