Police have been unable to link terrorists to a pipe bomb attack in Cologne Wednesday that injured 22 people, most of them Turkish. The majority of the victims have been released from the hospital.
No warning was given before the blast.
Investigators were unable to get much information out of the victims, 21 of whom were Turkish and one German. Six remain in the hospital.
Law enforcement officials said the pipe bomb was filled with nails roughly 10 cm (4 inches) long and exploded shortly before 4 p.m. on a busy shopping street in the Mühlheim neighborhood in northeastern Cologne. The blast destroyed store fronts and nearby cars in the mostly Turkish district.
Police said a wrecked bicycle that was found in front of a hair salon may have "played a role" in the blast. Media reports suggested the bomb might have been placed on the bike.
State prosecutors and law enforcement agents said they are being deliberately careful in looking at who might be behind the attack. So far, local police have been responsible for most of the investigation. Had there been suspicion of terrorist involvement, agents from Germany's Federal Office for the Protection of the Constitution would have taken over.
"We don't have any knowledge about the motive or suspects," Dieter Klinger, the head of the investigative team, told reporters.
Security sources have said the police investigation into the bombing was focusing on organized crime. German Interior Minister Otto Schilly said it was too early to draw a conclusion about a possible motive.
"The findings made so far by our intelligence authorities point not to a terrorist background, but to a criminal milieu," he said.
Police have assigned a relatively small force of 20 officers to investigate the attack, which indicates they do not believe terrorism is involved.
The blast occurred in the street in front of a three-story building containing both apartments and businesses and caused an estimated €100,000 ($120,758) in damage.Most of the injured had been in a pizza restaurant on the ground floor, according to a fire department spokesman.