Police in the western city of Essen say they are keeping an open mind about the reasons for an apparently deliberate explosion at a Sikh temple that injured three people late Saturday.

Essen police spokesman Lars Lindemann said Sunday that a masked man reported to have fled the scene hadn't yet been apprehended. Three people detained late Saturday were released after no link to the explosion was found.

Lindemann said police were investigating "in all directions" but there were no indications of a terrorist motive.

He said a 60-year-old man suffered serious but not life-threatening injuries in the blast and remains hospitalized. Two men aged 47 and 56 suffered slight injuries.

The victims were members of a wedding party that had held a ceremony at the temple earlier Saturday.