May 28 (Reuters) - Over 754,000 homes and businesses in

Texas, Kentucky and other states in between were without power

on Tuesday after storms battered the region over the long

Memorial Day holiday weekend, according to meteorologists and

data from PowerOutage.us.

Tornado-spawning thunderstorms that swept the Southern

Plains and the Ozark Mountains have killed at least 21 people

across four U.S. states.

Texas power company Oncor, a unit of California-based energy

company Sempra Energy, has the most outages with over

540,000 customers without power in the Dallas-Fort Worth area,

according to PowerOutage.us.

Oncor said it was "currently monitoring and responding to

outages caused by thunderstorms producing large hail and wind

gusts up 80 miles per hour (129-kilometers per hour) in the

Dallas-Fort Worth area and surrounding areas".

The utility said on its power outage website that it could

not estimate restoration times for many customers.

Major outages by state:

State Outages

Texas 592,000

Kentucky 81,000

Arkansas 39,000

Missouri 21,000

West Virginia 21,000

Total Out 754,000