Forecasters say Hurricane Maria has become a Category 5 storm as the eye nears Dominica.
The National Hurricane Center in Miami said Monday evening that Air Force Reserve hurricane hunter planes found that Maria had strengthened into a storm with 160 mph (260 kph) winds.
The hurricane is about 15 miles (25 kilometers) east-southeast of Dominica and moving west-northwest at 9 mph (15 kph).
University of Miami hurricane researcher Brian McNoldy says one key sign of Maria's growing strength is what center forecasters call "the dreaded pinhole eye." Maria's eye has shrunk to 10 miles (15 kilometers) in diameter
A smaller, tighter eye makes the hurricane spin faster. McNoldy says meteorologists saw a similar pinhole eye when Hurricane Wilma set a record for lowest central pressure -- a key measure of storm power -- in 2005.
Officials said Monday that the rationing is necessary to ensure everyone has access to basic items such as batteries, milk, canned foods, flashlights and other things. It does not apply to gasoline or other fuels.
Shelves at many stores were emptying out quickly as people rushed to finalize hurricane preparations. Many posted desperate pleas on social media for help in finding certain items.
Officials said some stores already were imposing their own rationing measures and stressed that more merchandise was scheduled to arrive on Monday to replenish shelves.
Elsewhere, Hurricane Jose continues to head north over the Atlantic off the U.S. East Coast, causing dangerous surf and rip currents. Tropical storm watches have been posted along the coast from Delaware to Massachusetts' Cape Cod.
The ocean is washing over parts of North Carolina's Outer Banks as Hurricane Jose passes well to the east.
The state Transportation Department said in a Facebook post Monday that the affected areas encompass Pea Island, Rodanthe, Avon and Hatteras village on Hatteras Island.
DOT is urging drivers to drive slowly through the water. All roads are passable.
The National Weather Service warns of dangerous rip currents along the coast.