Dec 25 (Reuters) - Thousands of residents were without power near Tacoma, Washington, after three electrical substations were vandalized, local authorities said on Sunday, adding that it was not yet clear if the Christmas Day incidents were linked.Deputies cited forced entry into the fenced-in area, with equipment vandalized but nothing taken from the sites, it said.Earlier this month, a utility in North Carolina reported outages from what local authorities said were orchestrated shootings now being investigated by federal law enforcement.The FBI has also been investigating shots fired near a power facility in South Carolina days later, and whether those two incidents could be related, NBC News and other local media have reported.Utilities nationwide have been strained by a severe cold weather system that swept across the country this week, leaving more than 300,000 without power from the winter storm."