A powerful snowstorm pounded the nation's capital and other mid-Atlantic states early Saturday, snarling down traffic and bringing travel to a virtual standstill, CNN reported. Buses and above-ground rail services were suspended in Washington, and only underground trains would run Saturday, transportation officials said. Cancellation of ground transportation comes a few hours after flights were canceled at the Washington-Baltimore area's three main airports and at Philadelphia International Airport. Delta Air Lines had suspended flights in and out of Washington, Baltimore, Maryland and Philadelphia, said Delta spokesman Anthony Black. There will be limited service to Philadelphia on Saturday, he said. The company hopes to get flights back in service by Sunday.