A makeshift bomb exploded at a Nogales, Arizona power substation Wednesday morning, destroying a diesel fuel tank and causing a massive federal investigation.

Agents from the FBI and ATF that specialize in bombings quickly reached the site after the blast at 9:30 a.m. Wednesday morning.  The explosion was strong enough to damage the tank and cause a diesel fuel spill but fortunately the bomb did not ignite the fuel.

Officials say had the fuel ignited it would have likely destroyed the substation.

Nogales police Lt. Carlos Jimenez said that the plant was critical for the area and had it been destroyed over 30,000 people would have been without power for days.

“The whole city of Nogales could have been compromised,” Jimenez said.

The blast did not cause any power disruptions and repairs should not cause the station to be off-line.