(CNN) -- Separatist rebels bombed an electricity transmission tower in the southern Philippines on Saturday, according to military spokesperson Lt. Stefani Cacho.

The tower supplies electricity to several towns in the region.

Rebels from the Moro Islamic Liberation Front, an Islamic militant group based in the Philippines, used four explosive devices but only 3 detonated, Lt. Cacho wrote in a text message to CNN.

The government of the Philippines has been involved in stormy peace negotiations with MILF since 2003.

Last month, armed men attacked a U.N. truck carrying food to the southern Philippines, killing the driver's assistant, according to the U.N. World Food Program.

-- CNN's Kathy Quiano contributed to this report.