Meanwhile, Hurricane Frances strengthened as it churned near islands of the northeastern Caribbean with ferocious winds.
The eight named storms this month — through Hermine — are a record, reports CBS News Correspondent Mark Strassmann.
The Virginia declaration made state resources available and put the Virginia National Guard on standby for possible duty.
"No reported deaths at this point and I have not heard of any major injuries," Bob Spieldenner of the Virginia Department of Emergency Management told CBS Radio News.
Richmond was inundated with more than 11 inches of rain in 10 hours, turning streets into rivers and trapping people in buildings.
"It looks like rapids outside our building," said Nick Baughan, who was stranded with about 20 other people on the second floor of the Bottoms Up pizza restaurant. "All of our cars have floated away."
"There were some people that were trapped by high water," said Spieldenner. "There were some I know of that were in an apartment complex that they had to get them out of, and then I think there have been some with individual homes that they were having to get them out."
"Hurricane Frances continues to move towards the west at about 15 mph. It's north of the Leeward Islands, and it should pass just to the north of the Virgin Islands and Puerto Rico later today and into Wednesday," said CBS News Meteorologist George Cullen.
The storm's outer bands of wind and rain were to begin affecting the islands during the night. On Monday schoolteacher Jesus Gimenez put up storm shutters on his hillside home to guard against flying debris.
"The more we get done, the less work it will be when it gets here," said Gimenez, 52, who also stocked up on groceries from evaporated milk to bottled water.
They're also stocking up again in Florida, in anticipation of Frances.
"I want to get mine ahead of time. While most of the people are at work, I'm out early," said shopper Julia Knowles.
"This is a very dangerous storm; strengthening is likely. It has sustained winds now of 125 mph, but it could strengthen into a category four hurricane at anytime over the next day or two," Cullen said, adding, "Florida would be the most vulnerable area, sometime over the weekend, probably Saturday into very early Sunday."
With rains from Hurricanes Alex and Charley and the remnants of Bonnie — all during August — portions of the Southeast have had rainfall totals that are several inches above normal for the month.
"If you throw another hurricane into the mix, there could be a lot of problems," said Mike Strickler, a National Weather Service forecaster in Raleigh, N.C.
Raleigh has already seen problems from Gaston.
"Branches came through the window," Connie Anders told CBS affiliate WRAL-TV.
In Punta Gorda, Fla., near Ft. Myers, high school kids now have get to school before dawn: So many schools were damaged during Hurricane Charlie — just two weeks ago — that students are on staggered shifts.
Carnival Cruise Lines said Monday it diverted three cruise ships to avoid the hurricane, as did Royal Caribbean International.
"I think anyone all along the southeast United States coast should closely monitor the progress of [Frances] and until it is determined where landfall will be, they should brush up on their hurricane plans," meteorologist Jamie Rhome of the National Hurricane Center told CBS Radio News.
For now, Virginians were struggling to recover from Gaston, which flooded the state's antiquated Emergency Operations Center with 4.5 inches of water and disrupted power briefly.
A stretch of Interstate 95 was closed and many streets were impassable, creating traffic jams that lasted from rush hour until well into the night. Many roads were still closed Tuesday morning.
Richmond police appealed to residents to call 911 only in a life-threatening situation after the system was swamped with hundreds of calls from residents. Some 92,000 electricity customers lost power.
This will be the wettest summer on record in some localities. Keith Lynch, a meteorologist at the National Weather Service said that Richmond had received 30.34 inches of rain since June 1, breaking the June-through-August record of 27.57 inches recorded in 1969.
Meanwhile, a weakening Tropical Storm Hermine was headed north in the Atlantic, prompting a storm warning for southeastern Massachusetts.