An Arizona Public Service (APS) employee was killed this week in a fire following an explosion in an underground electrical vault in downtown Phoenix. News sources say 41-year-old Ricardo Castillo died in the incident, which happened at approximately 10:30 p.m. on June 30. Another APS employee was able to escape the fire but suffered burn injuries to his hands and face. He was transported to the Maricopa Medical Burn Center where he was reported to be in in stable condition.

The Phoenix Fire Department firefighters responding to the fire were unable to extinguish it until  APS de-energized the electrical vault.

“We are deeply saddened to report that an APS employee died, and another was injured, in an accident on Sunday night while they were performing planned maintenance,” APS said in a statement.

Some buildings in downtown Phoenix were left without power until post-fire repairs were completed, including the Phoenix Municipal Building, the Maricopa County Administration Building and the Phoenix Civic Plaza South.

Arizona Public Service is the state’s largest utility company.

APS, Phoenix Police and Fire, and OSHA are investigating the incident.