Circuit Wire — a daily news update from the Circuit.

Prosecutors in the eastern German state of Saxony said on Monday, September 7, that investigators had found 21 homemade explosive devices near high-voltage power lines, according to a statement reported by Reuters. All of the devices were defused. Officers had been on high alert for days.

Nine of the devices were discovered over the weekend near high-voltage power lines south of the Graustein substation, in the Goerlitz district close to the Brandenburg border. Police and prosecutors described the finds in a joint statement. That discovery raised the total number of devices to 21.

German police said on Friday they were searching for a man who had sent letters claiming responsibility for a series of sabotage attacks on the grid, The Jerusalem Post reported. Officers found what appeared to be explosives at his home. The man remains at large.

Authorities examined other sites in parallel. A fire at a Berlin transformer substation earlier on Monday was traced to a technical fault, according to Police Commissioner Barbara Slowik Meisel, cited by Spiegel. Separately, in the western city of Wesel, police launched major assessment operations after the security fence around another substation was found cut open.

The finds follow a series of sabotage incidents on the German grid over the past week. They also come after a failed drone attack in August at Leipzig/Halle Airport that the government formally blamed on Russia. European officials increasingly treat such episodes as part of a broader campaign of hybrid attacks on critical infrastructure across the continent.

Substations and transmission lines are hard to guard because they stretch across open country and remote sites. Germany has been the focus of European fears about the vulnerability of critical infrastructure. Investigators have not publicly named a motive for the Saxony devices, and the search for the suspect remains active.

Want a weekly roundup of the major stories shaping the security industry? The On The Circuit newsletter is read by more than 12,000 protection professionals.

Spotted something we should cover? Send tips and feedback via circuit-magazine.com.