Washington, Jan 12 (IANS): At least 11 people were killed as powerful storms swept across southern parts of the US, with winds, tornadoes and floods.

Of the victims, a police officer and a firefighter were killed in Lubbock, Texas on Saturday morning, with another critically injured, after they were hit by a car while responding to a traffic accident, Xinhua news agency reported.

A man drowned in Oklahoma after he was swept away by floodwaters while getting out of his stalled truck, the Oklahoma Highway Patrol said on Saturday.

An elderly couple were found dead on Saturday near their demolished trailer in Louisiana, and another person was killed on an icy highway in Iowa after his truck overturned, local media reported.

Hundreds of thousands of people were left without power from Texas to Ohio.

Some highways were closed in Oklahoma and Arkansas due to flooding, and more than 1,200 flights were cancelled at Chicago's two international airports, according to the Chicago Department of Aviation's online flight-tracking website.

Many streams were already at or near flood levels because of earlier storms, and heavy rains could lead to flash flooding across the region, forecasters said.