A man has been arrested over the Stockholm truck attack.

At least four people have been killed and 15 injured - nine of them seriously, when a hijacked beer lorry was driven into crowds in a busy shopping street - then rammed into a department store.

Sweden's prime minister says it's being treated as an act of terrorism.

Taoiseach Enda Kenny has described the perpetrators as "cowards" whose views have no place in our society. 

This witness describes what happened: