Attacks on the nation’s power grid are suddenly on the rise, according to federal regulators, who are now weighing additional security requirements for power stations to fend off vandalism.

Some of the attacks were with gunfire which cut off electricity to thousands of customers since October.

The latest incident happened on Christmas Day in Washington state. Thousands of homes lost power after vandals broke into four power substations and damaged equipment, in one instance causing a fire. Law enforcement officials have yet to solve six prior attempts to sabotage electrical substations in both Washington and Oregon that began in mid-November.

Grid attacks are happening on the East Coast as well. The Christmas Day attack in Washington followed a Dec. 3 break-in at two Duke Energy electrical substations in Moore County, North Carolina. Vandals there caused significant damage with gunfire, cutting power for several days to more than 40,000 residents.

Shots were also fired at a Duke Energy hydroelectric dam in Ridgeway, South Carolina, on Dec. 8, but there was no damage.