Flash floods washing over the Midwest - KOBI-TV NBC5 / KOTI-TV NBC2

(CNN) – 19 tornadoes touched down from Texas to Oklahoma Monday night, causing widespread damage, and keeping millions on high alert. But the Midwest is not out of the woods yet. Severe thunderstorms, flooding and more tornadoes are in Tuesday’s forecast.

“It came so fast that we really didn’t hear so much,” said storm victim Brenda Rogers.

More than a dozen tornadoes were confirmed Monday night in Oklahoma and Texas, putting about four million people in harm’s way.

Many homes and businesses turned into piles of rubble in a matter of moments.

It’s not just tornadoes. Severe thunderstorms and heavy rainfall also an issue across the region.

And these storms aren’t finished yet. Flash flooding is threatening more than 50 million people from Oklahoma to Kansas.

Early Tuesday, the National Weather Service issued a flash flood emergency for the Tulsa area, including Tulsa, Rogers, Mayes, Wagoner, Osage, Pawnee and Washington counties.

The National Weather Service in Tulsa urged people in those areas to move to higher ground.

Water rescues were reported overnight into the early morning hours.

Shelters have opened in several counties for those having to leave their homes.