A man being held over a lorry attack in Sweden has now been arrested on suspicion of committing "terrorist crimes through murder".

Four people were killed and several others were left injured after a hijacked truck was driven into pedestrians and rammed into a department store in the city.

In response, security at borders has been heightened and there are more police patrols.

Sweden's prime minister Stefan Lofven says the country is in shock, but will not be intimidated: