A suitcase exploded near a reception center for migrants in southern Germany, on Wednesday, but the blast may have been caused by an aerosol can inside it, and there was no evidence of explosives being involved, police said.
The blast occurred about 200 metres (yards) from the centre in the Bavarian town of Zirndorf, where police were on the scene. No one was hurt in the explosion.
"There is no indication at the moment that a bomb was detonated in the suitcase," police said in a statement.
"It is possible it was a spray can inside the suitcase that caused the explosion. No one was reported injured."
Police said they were looking for a man around 30 years of age and a woman of about 25 who may have owned the suitcase
Authorities in Bavaria are on edge after three attacks over the past week.
On Sunday, a Syrian asylum seeker with suspected links to the Islamic State group blew himself up near a music festival in Ansbach, wounding 15 people.
Nine people were killed in a shopping centre shooting spree in Munich on Friday, just six days after four passengers on a train and a passer-by were wounded in an axe attack in Wuerzburg.
Bavaria has been a gateway for the influx of migrants and refugees to Germany, which saw a record 1.1 million people arrive last year.