At least 15 people were killed and 18 others were injured, five of them critically, on Wednesday, when a popular funicular in Lisbon derailed and crashed, according to Portugal’s health ministry.

The funicular, the Elevador da Glória, climbs a steep hill from the city’s historic Baixa district to reach panoramic views in the Bairro Alto neighborhood. The Lisbon Firefighters Regiment said that the accident was caused by “a cable that came loose” in the structure of the funicular, which lost control and crashed into a building.

In a statement, President Marcelo Rebelo de Sousa of Portugal expressed his condolences and solidarity with the families affected by what he described as a tragedy.

Mayor Carlos Moedas of Lisbon said the city was in mourning. “It’s a very difficult day for all of us,” he said.

According to local media reports, the accident took place just after 6 p.m., during the city’s rush hour. Images and footage posted to social media appeared to show one of the yellow cars flipped beside the rails and surrounded by debris and smoke. Passengers emerged from another car, which still appeared to be sitting on the rails.

The funicular, which opened in 1885, is part of a network of cars that run along Lisbon’s steep hills, carrying more than 3.5 million passengers a year, and have become emblematic of the city.

This is a developing story. Check back for updates.