New Delhi: India on Sunday expressed concern over an explosion at a Sikh temple in the German city of Essen that left three people injured. External Affairs Ministry spokesperson Vikas Swarup tweeted he was "distressed to hear of an explosion in a gurudwara in the Essen city of Germany". The nationality of the injured was not immediately known. "Our mission (in Germany) is following up with local authorities on ground situation," Swarup said. Police in Germany have said there were no indication that the explosion was a terrorist attack but said it may have been caused deliberately. Three people have been detained for questioning, the Independent.uk reported. A masked person was spotted fleeing the scene shortly after the blast around 7.00 p.m. (German time) on Saturday, the police said. The explosion took place as people were celebrating the Indian festival of Baisakhi. The temple had hosted a wedding earlier in the day and the injured were guests from the marriage party.