One of Lisbon's most iconic tourist attractions, the Glória funicular railway, has derailed and crashed. It is a popular tram-like form of transport that is designed to travel up and down steep slopes.

At least 17 people have been killed and about 20 injured, some critically.

It is not yet clear what caused the carriage to derail.

Here is everything we know so far:

A carriage derailed at around 18:15 (17:15 GMT) on Wednesday 3 September, near the city's Avenida da Liberdade boulevard.

More than 60 rescue personnel and 22 vehicles were deployed to the scene.

Officials say it is too early to determine what caused the crash, but Portuguese newspaper Observador reports that a cable came loose along the railway's route, causing it to lose control and collide with a building.

As smoke engulfed the area, people could be seen running away from the scene.

Images and footage show an overturned, crumpled yellow carriage lying on the cobblestone street, surrounded by emergency responders.

Some people were trapped in the wreckage, and had to be freed by emergency workers.

Exact information on who was riding the funicular at the time - and who may have been injured on the street - remains unclear but at least 10 nationalities are said to be involved.

Those taken to hospital include four Portuguese, two Germans, two Spaniards, one Cape Verdean, one Canadian, one Italian, one French person, one Swiss, one Moroccan and one Korean, the city's Municipal Civil Protection Service was quoted as saying by Portugal's Lusa news agency.

Portuguese media is reporting that a three-year-old child is being treated in one of Lisbon's hospitals, while the child's mother, who is pregnant, has been transferred to a maternity unit.

The Glória funicular can carry about 40 passengers and is extremely popular with tourists but it is also crucial for the city's residents, to help them travel up and down Lisbon's hilly streets.

It is not known how many people were onboard at the time of the crash, however.

A funicular is a type of railway system that allows travel up and down steep slopes, and in Lisbon, they are a crucial means of navigating the city's steep, cobbled streets.

The city's funiculars are a popular tourist attraction, as the bright yellow tram-like vehicles snake through the often-narrow, hilly streets.

The Glória funicular was opened in 1885 and electrified three decades later.

It travels some 275m (900ft) from Restauradores, a central city square, up to the picturesque streets of Bairro Alto. The journey takes just three minutes.

Unlike traditional funiculars, the two cars on the Glória route 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.

In an interview with BBC Radio 4's Today programme, Fabiana Pavel, who is president of a Lisbon residents' association, shared that her community is shocked.

She said the funicular is an important means of public transportation for those who live in Bairro Alto, "especially for people with reduced mobility as it allows them to easily climb a steep hill".

"At the time of the accident there may have been parents with children returning from school."

Ms Pavel added that the cable car is used disproportionately by tourists, leaving locals unable to use the service as a means of transport "because it has become a tourist attraction".

Lisbon Mayor Carlos Moedas has declared three days of municipal mourning for the victims of the incident.

Posting on X, he said: "I extend my heartfelt condolences to all the families and friends of the victims. Lisbon is in mourning."

Spain's Prime Minster Pedro Sánchez said he was "appalled by the terrible accident".

"All our affection and solidarity with the families of the victims and with the Portuguese people in this difficult moment," he wrote in a statement on X.

Portuguese President Marcelo Rebelo de Sousa said he "deeply regrets" the "fatalities and serious injuries" caused by the crash.

Pedro Bogas from Carris, the Lisbon Tramways Company, told reporters it was a "very a sad day, not just for the victims but also for their families".

"We have strict protocols, excellent professionals for many years, and we need to get to the bottom of what happened," he added.

European Commission President Ursula von der Leyen wrote on X: "It is with sadness that I learned of the derailment of the famous Elevador da Glória. My condolences to the families of the victims."