A total of 12 people were killed and 50 injured after a truck was driven into crowds of revellers at a Christmas market in Berlin on Tuesday. Islamic State claimed responsibility for the attack. The militant group's AMAQ news agency said that the executor of the operation in Berlin was a member of Islamic state (IS). <br/><br/>German police are investigating the attack. The police said, a 23-year-old suspect arrested last night may not have been the attacker and his blood and DNA does not match samples found inside the truck. Later, the police released the suspect. The news of the release was confirmed by the Chief Federal Prosecutor's office. Meanwhile, German Chancellor Angela Merkel said in a short statement that those behind the attack would be punished as harshly as the law allows.