Rescue efforts are underway in Indonesia after a boat capsized near the Mentawai Islands in West Sumatra, leaving 11 people missing, according to the local search and rescue agency.

The incident occurred late Monday morning, around 11am local time (04:00 GMT), when the vessel went down amid rough weather as it traveled between the towns of Sikakap and Tuapejat. Of the 18 people aboard, seven have been rescued so far, while the search continues for the rest.

Authorities say two rescue boats and dozens of personnel have been deployed to comb the area where the boat is believed to have sunk. Among the passengers were 10 local government officials.

“Our main priority is to search thoroughly around the suspected location of the accident to find all those still unaccounted for,” said Rudi, head of the Mentawai search and rescue team.

While officials have not confirmed the exact cause of the accident, maritime mishaps are not uncommon in Indonesia, a vast archipelago of around 17,000 islands. Contributing factors often include severe weather and insufficient safety measures.

This latest incident follows a string of deadly maritime accidents in the country. Earlier this month, a ferry with 65 people aboard sank off Bali’s coast, resulting in at least 18 fatalities.

In March, another vessel capsized in the same region, killing an Australian tourist and injuring others. Back in 2018, more than 150 lives were lost when a ferry sank in a volcanic lake on Sumatra Island.