Morning tidal flooding left King and Union streets underwater Monday in Alexandria. (Matt McClain/The Washington Post)

Virginia Gov. Ralph Northam on Monday ordered the evacuation of about 245,000 residents in flood-prone areas as Hurricane Florence strengthened on its path toward the East Coast.

Residents were to be evacuated by 8 a.m. Tuesday in the Hampton Roads area — including portions of Virginia Beach, Hampton and Norfolk — as well as part of the Eastern Shore. Northam (D) said he had requested 21 swift-water rescue teams from other states and activated 1,500 of the state’s 6,000 National Guard members, with the rest on standby.