A passenger ferry capsized on the Nile River in Sudan on Wednesday, leaving at least 15 people dead, the Sudan Doctors Network said, as rescuers continued searching for additional victims. The medical group, which tracks the country’s ongoing war, said the ferry sank in the Shendi district in northern Nile River province.

The Sudan Doctors Network said the ferry had at least 27 people on board, including women and children. It reported that at least 15 bodies had been recovered and that residents and rescue teams were still looking for at least six other people.

The group said six people survived the capsizing. It urged Sudanese authorities to deploy specialized rescue teams and equipment to accelerate the search efforts.

The ferry capsize renewed concerns about water safety in Sudan, where such tragedies on overloaded boats are not uncommon, according to the Sudan Doctors Network’s account.