Update at 5:05 p.m. — Dominion has confirmed to authorities that the loud boom was caused by a malfunctioning underground transformer. Due to redundancies in Rosslyn’s electrical system, power has been restored to buildings affected by the outage, according to scanner traffic. Road closures are expected to be lifted soon.
Earlier: Arlington County Police have closed N. Lynn Street in Rosslyn to traffic and pedestrians after an explosion was heard in the area.