Two more bodies were found late on Monday, an Indonesian official says, as volcanic activity hampers rescue mission.

“The total number of people who have died is currently 13,” Abdul Malik, head of Padang Search and Rescue Agency, told AFP news agency on Tuesday, adding that 10 hikers were still missing, while 52 have been evacuated.

The bodies of the two hikers were found late on Monday, he said.

The rescue mission is being hampered by further volcanic activity and bad weather.

“The volcanic ash has reached the foot of the hill, which is a challenge for the team. Both routes will be steep and slippery,” Malik said.

Eleven bodies were found on Monday near the crater of Mount Marapi on the island of Sumatra, while several others were found alive and carried down the mountain.

The volcano spewed an ash tower 3,000 metres (9,800 feet) – taller than the volcano itself – into the sky on Sunday. It was the deadliest eruption since 1979, when another one killed 60 people.

‘Mountain of Fire’

Mount Marapi, which means “Mountain of Fire”, is the most active volcano on Sumatra island. Between Sunday and Monday, 46 eruptions had occurred, besides one on Tuesday morning, state-run Antara News reported.

Indonesia experiences frequent seismic and volcanic activity due to its position on the Pacific “Ring of Fire”, where tectonic plates collide. The archipelago nation has nearly 130 active volcanoes.

For more than a decade, Indonesia’s volcanology agency had sent monthly letters warning the Ministry of Environment and Forestry and local conservation agency that climbers should keep a safe distance from the volcano’s peak, agency head Hendra Gunawan told Reuters news agency.

“The recommendation was to not climb up to the peak, that no one should go within 3km of the crater,” he told Reuters.

Officials from the volcanology body said it could only issue safety warnings and that it was up to the environment ministry and local authorities to enforce them.

The conservation agency, which is under the ministry, said permits to climb were given after getting the green light from several local agencies, including the West Sumatra provincial government and national disaster agency, as well as the Padang search and rescue agency.