"A bag with explosives was found in a truck used for the terrorist attack yesterday in Stockholm," SVT television reported citing several sources in the police.
Swedish Prime Minister Stefan Lofven said the attack was most likely an act of terrorism.
Last month, a man hit several people while driving on Westminster Bridge in the center of London before attempting to enter the Houses of Parliament, armed with a knife. After stabbing a police officer, who was later confirmed dead at the scene, the 52-year-old attacker was shot. Daesh claimed responsibility for the attack.
In December 2016, a Tunisian asylum seeker drove a truck into a crowd at a Berlin Christmas market, killing 12 people and injuring over 40 others. The 24-year-old was shot dead a few days later by police in Milan, Italy.