Houses are flooded in Miami-Dade County, Florida,on August 26. -Xinhua

At least seven people have been killed and some 1.4 million left without power since Hurricane Katrina hit southeastern US state of Florida on Thursday.

Media reported three people were killed by falling trees, and an elderly man died when his car crashed into a tree.

The reports said one person was found dead aboard his boat, one body was found trapped in a capsized houseboat and another was found floating in the water.

In addition, a couple and their three children were reported missing at sea during the storm, and Coast Guard members were searching for them.

Over one million homes and businesses lost power after the storm came ashore late Thursday, but authorities said it would take several days to restore power to those homes and businesses.

Schools and most offices in the state remained closed on Friday, and commuter train and bus services were suspended.

Katrina, which formed Wednesday over the Bahamas, was the second hurricane to strike Florida this year. Florida was hit by four hurricanes last year.