Utility workers from the Los Angeles Department of Water and Power installing an automated transmission system made an error that resulted in blackouts across much of Los Angeles.

Some two million people were affected by outages that came when workers connected wires inadvertently while cutting a group of cables.

According to comments attributed to Ed Miller, director of power-system operations and maintenance for the Los Angeles Department of Water and Power, “They cut wires that caused circuit breakers to trip.”

No one was injured in the incident and the bulk of power supplies were restored within a few hours.