(Cole) Powerful thunderstorms that included tornadoes, strong winds and hail killed at least two people Wednesday in the central United States.

There are also reports of multiple injuries, significant material damage and thousands of customers without power.

The US National Weather Service issued the first warnings for tornadoes and thunderstorms Wednesday evening in Oklahoma, Kansas and Iowa. Meteorologists advised the population to seek refuge.

Multiple tornadoes swept through central Oklahoma, including one that hit the towns of Shawnee and Cole on Wednesday night.

At least two deaths have been reported in Cole, McClain County, about 40 miles south of Oklahoma City. Some injured had to go to the hospital, but the results remain unclear.

Deputy Sheriff Scott Gibbons told the NBC network that it is “reasonable” to anticipate that the number of victims will increase, given the damage seen on the ground.

Power lines were ripped out, trees uprooted and multiple structures heavily damaged or destroyed. A university and an airport were hit in Shawnee.

About 17,000 customers remained without power in Oklahoma as of Thursday morning, according to poweroutage.us.

Local press reports that residents south of Oklahoma City said they were trapped in their underground shelters. Postal boxes were swept away and rescuers had to use a GPS system to find the addresses of the victims.

Two people hid in a manhole to escape bad weather in Cole and were not injured, according to local television.

New thunderstorms capable of giving birth to tornadoes are expected Thursday evening, according to the National Weather Service. Good-sized hailstones, strong winds and a few tornadoes are possible, meteorologists warned.

Some 3.5 million people call the area most at risk home, including the cities of Oklahoma City, Tulsa, Norman and Edmond, Oklahoma, and Omaha, Nebraska.