A ferry carrying families celebrating Mother’s Day and the Kurdish new year overturned on the Tigris River in the Iraqi city of Mosul on Thursday, killing at least 94 people, authorities said.

The dead were mostly women and children who struggled to swim in the fast-moving current, with the river swollen from heavy rains and the opening of the nearby Mosul Dam, the head of the civil defense authority in Mosul said. 

According to rescuers’ initial assessment, the ferry had been loaded far beyond capacity and tipped over as it traversed the river toward Mosul’s Tourist Island. At least 55 people were rescued, including 19 children.

Videos posted on social media showed people with their heads barely above the water fighting against the strong current as onlookers attempted to wade into the river to rescue them.

“Anyone who knows how to swim, jump into the water!” a man shouted in one video that showed smaller boats working to save the victims. 

Prime Minister Adel Abdul Mahdi released a statement expressing condolences to the families of the victims and promised an investigation that would be completed within 24 hours.

He later traveled to Mosul from Baghdad to meet with local security officials and politicians and announced a three-day national mourning for the victims.

Lt. Col. Raed Abdellatif, a spokesman for the civil defense authority, said an initial investigation showed that the boat had a maximum capacity of 50 people but had been loaded with more than 100.

Abdellatif said the boat’s operator ignored  Ministry of Water Resources warnings that were broadcast on state media for two days that water levels would be high because of the opening of the Mosul Dam.

The ferry did not appear to have any life vests onboard, he said, and the majority of the passengers could not swim.

The tragedy was the latest setback for a city that has struggled to rebuild after it became, in 2017, the center of the bloodiest battle against the Islamic State in Iraq. The militant group had occupied Mosul for three years and considered it the de facto Islamic State capital in Iraq — imposing its harsh rule over more than 1.5 million people, by far the largest territory the Islamic State controlled. 

It took Iraq’s military, backed by relentless U.S. airstrikes and advisers on the ground, nine months to reclaim Mosul. In the process, the western half of the city was leveled and has largely remained that way amid a halting reconstruction effort by Iraq’s government. Independent investigations have concluded that up to 10,000 civilians died in the fighting. 

Mosul’s eastern half was mostly spared and sprang back to life in a short time. People began enjoying small pleasures that were banned under the Islamic State.

Thursday’s ferry ride to an island in the Tigris with amusement park rides, which opened in April, would have been exactly the type of public revelry the militants forbade. This year, Mother’s Day and Nowruz, the Kurdish and Persian new year, fell on the same day, and families throughout Iraq are celebrating a long weekend.