At least four suspects have been killed in Cambrils, a town south of Barcelona, in an operation responding to a terror attack in Barcelona in which 13 people have been killed and more than 100 others injured, the Spanish police said Friday.

The news came hours after police launched a manhunt for the driver of a van that mowed through crowds of tourists on one of Barcelona's busiest thoroughfares Thursday.

"We are working on the hypothesis that events in Cambrils respond to a terrorist attack. We have killed its alleged perpetrators," Catalan police wrote on Twitter.

Through social networks, Barcelona's police have asked residents in Cambrils and the adjacent region to stay at home to avoid danger.

"If you are in Cambrils avoid going out. Stay home, stay safe," the police tweeted.