 -- A "large" and "extremely dangerous" tornado tore through western Alabama Tuesday afternoon, likely part of a storm system that also caused reported tornadoes in eastern Mississippi, the National Weather Service announced.

The tornado hit near the town of Aliceville and moved northeast at 45 mph, the NWS said. A total of six tornadoes have been reported in Mississippi and Alabama, but it's likely that they're all from the same long-tracked system.

The NWS in Birmingham, Alabama, said significant structural damage was reported near Aliceville and there was damage at the federal prison.

It was unclear if there were any injuries.

A tornado watch lasting until 10 p.m. was issued for parts of Alabama, Mississippi, Tennessee, and some areas in Florida and New Orleans.

Images posted to social media showed uprooted trees and dark, ominous clouds.

A total of 21 million Americans were at risk from Alabama to Indiana, and eight states have issued tornado warnings in anticipation of tornadoes and damaging winds.

Earlier, the same storm system brought winter warnings to 11 states from New Mexico to Michigan. A blizzard warning has been issued for five of those states, from Kansas to Minnesota.

The severe weather will end by Wednesday morning, but it may bring heavy rain and possible to the eastern seaboard.