Prosecutors in the eastern German state of Saxony said on Monday that authorities had found a total of 21 explosive devices as part of their investigations into attacks on the electricity grid that have kept authorities on high alert for days.All devices were defused, prosecutors said in their statement.Power grid targeted nationwideGerman police said on Friday they were searching for a man who sent letters claiming responsibility for a series of sabotage attacks on the power grid last week after they found what appeared to be explosives at his home.Berlin police said on X they are seeking to establish whether a fire affecting a construction site and a substation in the Moabit district on Monday was accidental or arson.Authorities added that the power supply was currently not affected.Separately, Bild newspaper reported that police in the western city of Wesel have launched major assessment operations after the security fence around another transformer substation was found to be cut open.