No arrests have been made for the vandalization of four power substations on Christmas Day, which caused 14,000 people in Tacoma, Washington, to lose power.

Suspects broke into a fenced area of the first substation around 2:30 a.m. That substation belonged to Puget Sound Energy. Officials said power was restored around 5 a.m., and about 7,700 customers were affected.

The second vandalization occurred in Spanaway, Washington, around 5:30 a.m. However, Tacoma Public Utilities (TPU) did not report the incident until 11:30 a.m.

When the Pierce County Sheriff’s Office arrived, equipment was on fire and appeared to have been vandalized. Responders put out the fire, and it took until noon to restore power to 2,700 customer households — approximately 4,700 people.

Police said that sometime during the vandalism spree a third TPU substation was also damaged.

Authorities were then called to a fire at a fourth power substation. When they arrived, they said, “the fenced area was broken into and the equipment vandalized.”

Puget Sound Energy reported the fire around 7:30 p.m. The Pierce County Sheriff’s Office explained that response crews, including firefighters and energy workers, were dispatched, and the substation was deemed “secured” after the fire was contained.

Power was lost in two neighborhoods, Graham and Kapowsin, leaving some in the dark until midnight during the holidays.

This is not the first recent incident of power substations being vandalized. Earlier this month, two substations owned by Duke Energy in North Carolina were taken out, causing 40,000 people to lose power.

Dr. Granger Morgan, a professor of engineering at Carnegie Mellon University who chaired three National Academy of Sciences reports on the power grid for the U.S. government, observed, “We’ve known the power system is very vulnerable to physical attack, and we’ve known this for decades.”

No suspects have been found in this latest string of incidents, and it is unclear whether the vandalisms were related.

Police released a statement urging community members to report anything they may know.

“All law enforcement agencies in the county have been notified of the incidents and will be monitoring power substations in their area,” they assured the public.