At least 15 people have been killed and 18 others injured after a carriage on Lisbon's famous Gloria funicular derailed and crashed, emergency services said.
Portugal's emergency medical service authority said that five of those injured were in a serious condition. The remaining thirteen, including a child, sustained minor injuries.
Several people were earlier said to have been trapped at the scene. They have all since been freed, authorities said.
Spain's Prime Minster Pedro Sánchez said he was "appalled by the terrible accident". Lisbon's mayor, Carlos Moedas, said the capital was "in mourning", adding it was a "tragic moment for the city".
Emergency services said foreigners were among those killed were, although nationalities could not be confirmed.
It is unclear how many people were on board at the time of the cable railway crash, which occurred near the Avenida da Liberdade around 18:05 on Wednesday evening.
Footage shared widely on social media showed the bright yellow carriage overturned and almost entirely destroyed. People could be seen fleeing the area on foot as what appears to be smoke filled the air.
One witness told Portuguese newspaper Observador the vehicle was "out of control, without brakes".
"We all started running away because we thought [the carriage] was going to hit the one below," said Teresa d'Avó.
"But it fell around the bend and crashed into a building."
Another told Portuguese TV channel SIC that the funicular hit a building as it sped down the steep street "at full speed".
"It hit a building with brutal force and collapsed like a cardboard box; it had no brakes," the woman said.
The Lisbon authorities say it is too early to determine the cause of this incident.
However, Observador reported that a cable came loose along the railway's route, causing it to lose control and collide with a nearby building.
The transport company which runs the funicular, Carris, said it had opened an investigation, adding that "all maintenance protocols" had been respected.
Portuguese President Marcelo Rebelo de Sousa issued a statement expressing his "sympathy and solidarity with the families affected by this tragedy".
European Commission President Ursula von der Leyen also sent her condolences to the families of the victims.
A funicular is a type of railway system that allows travel up and down steep slopes.
The two cars on the Gloria funicular are powered by electric motors. They are attached to opposite ends of a haulage cable meaning that as one travels downhill, its weight lifts the other, allowing them to ascend and descend simultaneously.
The Gloria funicular is one of the most famous sights and tourist attractions in Lisbon. It was opened in 1885 and electrified three decades later.
The iconic yellow vehicles are a crucial part of a city as hilly as Lisbon. They snake their way up many of the cobbled streets.
This particular one that crashed travels some 275m (900ft) from Restauradores, a square in the middle of Lisbon, up to the picturesque, cobbled streets of an area called Bairro Alto - or high neighbourhood - taking just three minutes to make the journey.
It, and the other funiculars, are used by Lisbon residents but they are also extremely popular with tourists – and at the end of the summer, the Portuguese capital is very busy indeed.
