Barcelona - The attack took place in central Barcelona. 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. A video posted to social media shows more than 12 injured people lying on the ground outside souvenir shops in front of Maccabi restaurant in Las Ramblas. As well as some uniformed emergency service personnel attending to the injured, a number of people casually dressed in shorts and t shirts can be seen offering help and tending to the wounded. In a tweet , Catalan police confirmed they were dealing with a terrorist attack. "Terrorist attack confirmed," they said. "The terrorist attack protocol has been activated." For now we don't know who was responsible for the attack, nor what the motive was. However, we do know that the use of vehicles to drive into civilians is a mode of attack hugely difficult to stop. Atrocities involving vehicle attacks have been carried out in France, Germany and Britain. Such vehicle attacks generally require very little planning, and no wider network, leaving little or no opportunity for the authorities to detect and stop them. Las Ramblas was full of people, is largely or wholly open, with few obstacles to block the path of any vehicle. Options to make a vehicle attack harder include making renting vehicles harder and placing barriers to limit how far an attacker could drive as they mow civilians down.