WASHINGTON - Train services were canceled and workers scrambled to protect power lines in Washington on Thursday as Hurricane Irene threatened the US capital days after it was rattled by a rare earthquake.

Irene, a major Category 3 hurricane now battering the low-lying Bahamas in the Atlantic southeast of Florida, was expected to make landfall on Saturday in North Carolina, with its high winds raking the heavily populated mid-Atlantic seaboard where Washington and New York were vulnerable.

A surfer rides a wave as rain bands from Hurricane Irene passes off the Florida coastline in Deerfield Beach, Florida August 25, 2011. [Photo/Agencies]

The 5.6 million residents in the Washington metropolitan area would be hit by heavy storms on Saturday and Sunday, warned weather forecasters and local officials. Irene was not expected to keep people away from their jobs on Friday.

Mayor Vincent Gray used Twitter to urge residents to study emergency evacuation routes from Washington and tell them that the mostly low-lying city would make sandbags available on Friday and Saturday.

The National Hurricane Center put the Washington metropolitan area and coastal Maryland to the east of the capital on hurricane watch for Sunday.

Handout image courtesy of NOAA shows a visible view of Hurricane Irene captured by the GOES-East satellite, August 24, 2011. Irene battered the Bahamas on Wednesday on a track to the North Carolina coast that forecasters say could threaten the densely populated US Northeast, including New York, starting on Sunday.  [Photo/Agencies]

Virginia and Maryland, which border Washington, declared a state of emergency, while local authorities ordered the mandatory evacuation of the beach resorts of Ocean City, Maryland, and Chincoteague, Virginia.

Electric power provider Pepco Inc said it had requested 600 emergency workers from other regions, and had already deployed 150 of them, to prepare for Irene's heavy rain and high winds that "could cause widespread and extended power outages.

"The subsequent restoration could be a multi-day event," the utility warned customers on its website, urging them to ensure adequate supplies of prescription medicines and infant supplies.

The Washington Metropolitan Transit Authority said it had prepared sandbags for flood-prone subway stations, inspected pumping facilities and called up extra staff for the weekend to prevent disruption to bus and subway services.

Railway operator Amtrak canceled trains operating south of Washington for Friday, Saturday and Sunday.

"Additional cancellations may be necessary in the coming days as the major storm moves north," the railway said in an alert on its website.

Most schools in Washington had reopened on Thursday after being closed two days for safety inspections of 126 school buildings due to Tuesday's 5.8 magnitude quake. The tremor was centered in Mineral, Virginia, about 90 miles (145 km) southwest of Washington.

The largest quake in Virginia since 1897 caused damage to well-known buildings, including cracks to the top of the Washington Monument, a prime tourist attraction.