Latest: Man arrested in connection with Stockholm attack

Latest: A man has been arrested in connection with this afternoon's truck attack in Stockholm in which four people were killed and around 12 injured.

What we know so far:

• A truck has crashed into people in the shopping district of Drottninggatan, in central Stockholm;
• The truck was deliberately driven into crowds of shoppers, security sources have told media;
• Four people have died and 15 people have been injured;
• A man has been arrested in connection with the truck attack
• The country's intelligence service said there was "a large number of injured";
• Shots have also been heard in a separate incident 20 minutes walk from truck crash;
• Swedish Prime Minister Stefan Lofven says everything indicates the truck crash is "a terror attack";
• Nobody has been arrested, but police are questioning two people;
• The truck had been hijacked from Swedish beermaker Spendrups earlier;