Local reports said a blast ripped through the 18,000–dwt Palu Sipat/Pertamina 1025 (built 2000) while it was undergoing repairs at the WNS yard in Belawan on Monday.
Three men were killed instantly and a fourth died in hospital from severe burns.
It was not clear what caused the accident or how badly damaged the ship is.
Pertamina confirmed the incident.
An investigation has begun.
