At least 13 people were killed after a van plowed into crowds in Barcelona’s Las Ramblas avenue in the city center on Thursday.
Cadena Ser, a radio station, and other media organizations said there were at least 10 dead. A police spokeswoman could not immediately confirm the number of casualties.
Police said on Twitter that multiple people were dead and injured and the attack is being treated as a terrorist attack.
Europe has been hit by a series of attacks using vehicles in the last two years, including deadly incidents in Nice and two in London.
Videos on social media showed a van traveling with its side door wide open at high speed down a pedestrian area of Barcelona’s popular Las Ramblas district.
A police spokesman said that they were not exactly certain what happened.
Newspaper El Pais reported that two suspects in the incident had barricaded themselves in a nearby restaurant.
Authorities are warning people to stay clear of the area.