Power has been restored to over 5,000 Unitil customers who were in the dark early Sunday evening, as emergency power restoration crews were dispatched to the area continue efforts to determine the cause.

At 7:30 p.m. Sunday, Unitil spokesman Alec O'Meara said an estimated 5,300 customers in the communities of Seabrook, Hampton, Hampton Beach and others were without power. O'Meara said crews believed a substation issue was to blame, and they performed switching operations to restore power to all customers by 9:45 p.m.

A cause has yet to be determined.