Three people ⁠were killed ⁠and one was ⁠injured in an accident during lifeboat maintenance work at a floating storage and offloading (FSO) vessel operated by Malaysian state energy ‌firm Petronas on Sunday, the firm said.

Petronas, or Petroliam Nasional Berhad, said in a statement on Monday the incident occurred around 12.50pm at FSO Sepat off Terengganu state on the east coast of Peninsular Malaysia.

Three ‌workers were pronounced dead on arrival at the hospital, while the injured ‌staff member was evacuated for medical treatment and ⁠remains ⁠under observation, Petronas said.

“Investigations into the cause of the ‌incident are ongoing in coordination with the relevant authorities,” it said.

The victims were believed to have boarded a lifeboat on the platform to descend to the sea for maintenance work. However, a rope or hook attached to the boat is believed to have come loose, causing them to fall into the sea.

Those who died were Ahmad Fiqri Zakaria, 38, Muhammad Faezuan Hakim Mohammad Bustamam, 28, and Nik Muhammad Hafifi Asri Ab Majid, 38.

Another victim, Mohd Taufik Mohd Ruslan, 37, was reported to have been seriously injured. He is still receiving treatment at the Sultanah Nur Zahirah Hospital (HSNZ).