At least two sailors died and three others are reported missing after two ships collided off the coast of Singapore, BBC reported. A search and rescue operation involving three patrol craft and an Air Force helicopter is underway, a statement by Singapore’s Marine Port Authority said.

The collision was between an Indonesian-registered tanker carrying 26 crew members from the country and a Dominican-registered dredger carrying 11 crew members of Chinese and one of Malaysian origin. Seven of the Chinese nationals have been rescued and are undergoing treatment at a hospital. The Dominican vessel capsized and was partially submerged, while the tanker was damaged on one side but none of its crew members were hurt.

Shipping operations in the area were not affected by the incident.

The incident came after a collision between a United States Navy ship with an oil tanker near Singapore in August. Ten US crew members had died in that accident.