An explosion went off close to an office for migration in the town of Zirndorf near Nuremberg on Wednesday, German broadcaster Bayerischer Rundfunk reported, adding that it was not yet known whether there were any casualties.
The broadcaster said on its website that a suitcase filled with aerosols was detonated, adding that it was unknown who had caused the explosion.
There was no word on any injuries.
Police said they were searching the perimeter for two people of interest - a man aged about 30 and a woman aged about 25.
Both were seen by witnesses pulling suitcases with them.
The area is in northern Bavaria, which has seen two attacks claimed by the Daesh group in the past 10 days.