Two incidents that disrupted power distribution systems in the west and east of Germany are being invested as possible sabotage, authorities said.

Multiple explosive devices were found Tuesday morning at a substation near the Jänschwalde coal-fired power plant in Brandenburg in northeast Germany. No general power outage resulted, but a few of the devices caused short circuits, authorities said.

Separately, a short circuit that caused several power lines to go out of service Tuesday evening at the Bergheim power substation near Cologne in western Germany appeared to be a deliberate act, police said, adding there was no general power outage.

“Based on the current state of the investigation, we are not assuming a technical defect, but rather a deliberate act, a crime,” the Essen police said of the Cologne outage, according to German press agency dpa.

RWE, a company operating coal power plants that utilize the Bergheim substation, said five coal-fired units with a combined capacity of 4,200 megawatts were taken offline and are expected to be working again by the weekend.

German power infrastructure has previously been affected under similar circumstances. Suspected left-wing extremists set fire to high-voltage lines near a power plant in southwest Berlin in January.

The country is on high alert after the German government on Tuesday blamed Russia for an attempted attack at Leipzig/Halle Airport on Aug. 4 using a drone laden with explosives.

Brandenburg Interior Minister Jan Redmann suggested possible foreign involvement, telling German media that authorities “cannot rule out any perpetrators” in Tuesday's attack.

“This is a hybrid threat we are currently experiencing, and therefore we cannot rule out the possibility that foreign powers are behind it,” Redmann said, according to dpa.