German investigators search for Berlin market attacker

From left: Ulrike Trautwein of the Evangelican church, Archbishop of Berlin, Heiner Koch, Imam Kadir Sanci, and Bischop Markus Droege hold hands as they attend a memorial service in the Kaiser-Wilhelm Memorial Church in Berlin, Tuesday Dec, 20, 2016 to remember the victims of an attack with a truck at a Berlin Christmas market on Monday. ( Michael Kappeler/Pool Photo via AP) (The Associated Press)

The Brandenburg Gate is illuminated in the colors of the German flag in Berlin, Germany, Tuesday, Dec. 20, 2016, the day after a truck ran into a crowded Christmas market and killed several people. (AP Photo/Markus Schreiber) (The Associated Press)

From right: German President Joachim Gauck, Chancellor Angela Merkel and the President of the German Parliament, Norbert Lammert, and other politicians attend a memorial service in Berlin's Kaiser-Wilhelm Memorial Church Tuesday Dec. 20, 2016 for the victims of a truck attack on a crowded Christmas market the day before, killing several people. ( Michael Kappeler/Pool Photo via AP) (The Associated Press)

German investigators are searching for the perpetrator or perpetrators of Monday's attack on a crowded Berlin Christmas market after a man arrested soon after the rampage was released for lack of evidence and the Islamic State group claimed responsibility.

The attack on the market next to the Kaiser Wilhelm Memorial Church in the center of the capital left 12 dead and 48 injured. Shortly afterward, a Pakistani man was detained based on a description from witnesses of a suspect who jumped from the truck and fled. But he was freed Tuesday after prosecutors couldn't find evidence tying him to the attack.

Police in Berlin said they had received 508 tips on the attack as of Tuesday night. But it wasn't clear Wednesday whether prosecutors had any concrete leads.