Millions of people in the central United States are bracing for powerful storms Monday including long-track tornadoes, hurricane-force winds and baseball-sized hail, forecasters said.

Much of Oklahoma and parts of Kansas are at the greatest risk of bad weather — including areas in Oklahoma, such as Sulphur and Holdenville, still recovering from a tornado that killed 4 and left thousands without power late last month. Both the Plains and Midwest have been hammered by tornadoes this spring.

In all, nearly 10 million people live in areas under threat of severe weather, the National Weather Service’s Storm Prediction Center said. Forecasters there issued a rare high risk for central Oklahoma and southern Kansas.

With the forecast, Oklahoma City Public Schools and several metro-area school districts began canceling all after-school and evening activities. Oklahoma’s State Emergency Operations Center, which coordinates storm response from a bunker near the state Capitol, remains activated from last weekend’s deadly storms, and the state’s commissioner of public safety told state agencies to let most state workers across the state leave early on Monday.