A van has crashed into a crowd of people in central Barcelona, with Spanish media saying there have been multiple deaths and injuries, and reports at least one armed man subsequently entered a restaurant in the area.

Spanish police, who said they were treating the incident as a terrorist attack, said people had died in the “massive crash” on Las Ramblas, a wide boulevard in an area of the city popular with tourists.

Television pictures show that a van came to a halt on top of a Joan Miro mosaic, half-way down the Ramblas – meaning that it would have covered more than 500 metres.

A photograph shown by public broadcaster RTVE showed three people lying on the ground in the street, apparently being helped by police and others. Catalonia’s TV3 station reported two dead and several injured.

The van entered Las Ramblas where it meets the Plaça de Catalunya, then drove towards the port area.

Catalan police have tweeted: “We can’t confirm a motive for the events that have taken place in Barcelona, but we have activated the protocol used to respond to attacks.”

Local media continue to talk of at least two dead and many injured. Ambulances and emergency vehicles are still arriving at the scene. The vehicle only seems to have managed to drive down only some 70 metres of the boulevarde before it crashed. The Ramblas boulevarde is more than one kilometre long and is usually packed at this time of year with tourists.

According to early reports, the vehicle sped down the centre of the road, which is usually packed with people, until it hit a newspaper kiosk and stopped.

Witnesses spoke of panic and seeing people covered in blood. Several pushchairs could be seen abandoned at the side of the street.

Eyewitness Jordi Lino was on a bus going down the Ramblas: “First I saw people running and then the van,” he said. “There were injured people in the middle of the Ramblas.”

A taxi driver told TV3 that he saw people being run over by the van.

TV3 said police sources had confirmed to it that one armed man was holed up in a Turkish restaurant near Las Ramblas and the Boqueria market.

But Catalan police say that reports of a shootout in the Corte Inglés department store were untrue. They are warning people to follow official sources for updates.

At this stage police are saying the number of injured people is unknown.

Metro stations and shops close to site of the crash were closed.

The spokeswoman for a chain of ten restaurants in the area said that some 600 people were stuck inside their restaurants, waiting for permission from the police to leave. Those people may be having trouble communicating with friends because mobile phone coverage in the area is saturated.

The Spanish newspaper El Pais, citing police sources, said the driver of the vehicle fled on foot.

Catalan emergency services said people should stay away from the area around Plaça de Catalunya.

Local police in Barcelona have asked people to communicate by social media and messages, as mobile telephone coverage is now saturated.

Video from mobile phones shows panicked, screaming tourists fleeing through the narrow streets beside the Ramblas.

TV3 says there are unconfirmed reports that a second van was following it but then drove off.

Las Ramblas, a street of stalls and shops that cuts through the centre of Barcelona, is one of the city’s top tourist destinations. People walk down a wide, pedestrianised path in the centre of the street, but cars can travel on either side.

Spain has so far been spared the kind of extremist violence that has occurred in nearby France, Belgium and Germany, but it was hit by what is still Europe’s deadliest jihadi attack in March 2004, when bombs exploded on commuter trains in Madrid, killing 191 people in an attack claimed by al-Qaida-inspired extremists.

The latest crash follows terrorist attacks with vehicles in France, Germany and the UK. Last July 86 people were killed in Nice, when a 19-ton truck mowed down people on the beach front. A Christmas market in Berlin was the scene of a similar atrocity in December, when 12 people were killed by a truck packed with steel. In London a speeding van hit pedestrians before attackers launched a knife attack in cafes and restaurants at Borough market in June. Eight people lost their lives in the attack, while at least 48 were wounded.

Vehicles have been used in several terrorist attacks in Europe in recent years, including a massacre that claimed 86 lives in the French city of Nice.