UPDATE: Police in Spain stop second attempted attack

BARCELONA (CBS NEWS) - UPDATE: With the country on edge and the driver of the van on the loose, authorities in a coastal city southwest of Barcelona reported an incident early Friday that was being treated as a possible terror attack. Catalan police tweeted that four terrorists were killed early Friday in Cambrils and a fifth person is in police custody. Authorities said there is an ongoing police operation, but the situation is under control. Six civilians were injured, two of them seriously, Catalonia emergency officials said. Cambrils is a coastal city about 115 kilometers southwest of Barcelona. UPDATE: The Catalan government's minister of the interior, Joaquim Forn, says 13 people have died and more than 50 have been injured. PREVIOUS: Police in the northern Spanish city of Barcelona say a white van has jumped the sidewalk in the city's historic Las Ramblas district, killing multiple people. Police are treating the incident as a terror attack. "We confirm the terrorist attack," Catalan police said. "The protocol for terrorist attacks has been activated." Police confirm fatalities were a result of the crash, but did not clarify how many people died. Citing police sources, the Reuters news agency reported at least 13 people were killed in the attack. A Barcelona city councilor says 32 others were injured. Ten of the victims sustained serious injuries. An official death toll has not been released. In a photograph shown by public broadcaster RTVE, at least five people were lying on the ground in the street Thursday afternoon and were apparently being helped by police and others. Videos of the scene recorded people screaming as they fled. At this time, the extent of the victims' injuries remains unclear. On Twitter, Spanish Prime Minister Mariano Rajoy said he is in contact with authorities and the priority is to attend to the injured. Reuters reports two armed men reportedly entered a restaurant following the crash. Spain's El Pais newspaper, citing police sources, says perpetrators of the van incident are holed up in a bar. Armed police ran down the streets and through a market, checking in stores and cafes, presumably in search of them. Catalan Emergency Services have asked authorities to close train stations in the area close to the crash site. Las Ramblas, a street of stalls and shops that cuts through the center of Barcelona, is one of the city's top tourist destinations. People walk down a wide, pedestrianized path in the center of the street, but cars can travel on either side. Authorities are asking people not to go near the area. Keith Fleming, an American who lives in Barcelona, was watching TV in his building just off Las Ramblas when he heard a noise and went out to his balcony. "I saw women and children just running and they looked terrified," he said. He said there was a bang -- possibly from someone rolling down a store shutter -- and more people ran by. Then police arrived and pushed everyone a full block away. Even people leaning out of doors were being told to go back inside, he said. Fleming said regular police had their guns drawn and riot police were at the end of his block, which was now deserted. "It's just kind of a tense situation," Fleming said. "Clearly people were scared." Carol Augustin, a manager at La Palau Moja -- an 18th-century place on Las Ramblas that houses government offices and a tourism information center -- said the van passed right in front of the building. "We saw everything. People started screaming and running into the office. It was such a chaotic situation. There were families with children. The police made us close the doors and wait inside," she said. Cars, trucks and vans have been the weapon of choice in multiple extremist attacks in Europe in the last year. The most deadly was the driver of a tractor-trailer who targeted Bastille Day revelers in the southern French city of Nice in July 2016, killing 86 people. In December 2016, 12 people died after a driver used a hijacked trick to drive into a Christmas market in Berlin. There have been multiple attacks this year in London, where a man in a rented SUV plowed into pedestrians on Westminster Bridge, killing four people before he ran onto the grounds of Parliament and stabbed an unarmed police officer to death in March. Four other men drove onto the sidewalk of London Bridge, unleashing a rampage with knives that killed eight people in June. Another man also drove into pedestrians leaving a London mosque later in June.