German police say a suitcase exploded Wednesday near a refugee center in Zirndorf, a Nuremberg suburb about 20 miles from where a suicide bomber injured 15 people on Sunday.

No injuries have been reported, but police were looking for a man and a woman believed to be the suitcase owners. Police said the burned remains of the suitcase contained clothing and the remains of a spray can but no explosives.

Police did not know if the suitcase was meant to be brought into the center or was being brought out when it exploded. A nearby resident extinguished the fire and called the authorities, who summoned explosives experts to the scene, according to a Bavarian police statement.

On Sunday, a 27-year-old Syrian refugee who had pledged allegiance to the Islamic State group detonated a bomb outside a music festival in Ansbach, injuring more than a dozen people and killing himself. Bavarian Interior Minister Joachim Herrmann said a video was found on the bomber’s phone in which he pledged allegiance to the Islamic State group.

Bavarian police were still investigating whether the man had any accomplices but said there was no known connection between the Ansbach bombing and Wednesday’s explosion in Zirndorf.

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