Indonesian rescuers are searching for eight people who went missing at sea while traveling to Anak Krakatau volcano to cover its latest eruption, officials said Wednesday.

The missing group includes five journalists, two boat crew members and a guide. They were traveling by speedboat from Carita in Banten province to the volcanic island in the Sunda Strait.

Banten Search and Rescue Office chief Al Amrad said the last message from the group was received by a journalist’s relatives at 6:13 p.m. Monday, saying they had reached waters near Anak Krakatau.

Their last known location was about 18.5 kilometers from the coast. Rescue teams have been searching since Tuesday but have yet to locate the boat or establish contact with those aboard.

The journalists work for Indonesia’s Antara news agency, Turkey’s Anadolu Agency, Merdeka and iNews, while another is a freelance photographer.

Anak Krakatau’s initial eruption ended Sunday but the volcano has continued to erupt intermittently, sending lava, ash and glowing volcanic material into the air.

The eruption forced airport closures on Sunday and Monday, disrupting nearly 2,961 flights and affecting around 341,000 passengers.

Authorities have also allowed schools in areas affected by volcanic ash to temporarily shift to online classes.

Anak Krakatau, meaning “child of Krakatau,” emerged from the remains of the volcano whose massive 1883 eruption devastated the surrounding area and contributed to global cooling.

An eruption in 2018 triggered a tsunami that killed at least 430 people in Sumatra and Java. The volcano has remained at Indonesia’s second-highest alert level since July, with authorities advising people to stay at least 3 kilometers from the crater.

Indonesia has more than 120 active volcanoes and frequently experiences eruptions because it lies along the Pacific “Ring of Fire.”