At least two people were killed in Oklahoma Monday as tornadoes spawned by a strong series of storms hit the Great Plains, destroying homes, overturning vehicles and stripping the bark from trees.

The weather was so violent that forecasters declared a "tornado emergency" for communities in the path of one of the twisters. The Storm Prediction Center said more than 20 tornadoes were reported across five states.

"You are in a life-threatening situation," forecasters declared while warning the communities of Roff, population 725, and Hickory, population 71, which were ultimately spared major damage. "Flying debris will be deadly to those caught without shelter."

Other places weren't as lucky, however, and two people lost their lives as a result. One was an elderly man believed to be in his upper 70s from Garvin County. Officials said he died when a large, fast-moving tornado swept through the county and hit a home near Wynnewood. That storm, caught on video by several storm chasers, appeared white against the dark clouds of a supercell storm.

The tornado also trapped six people under debris south of Wynnewood, according to the National Weather Service, adding that multiple homes were destroyed between Elmore City and Interstate 35.

Meanwhile, according to the Johnston County Sheriff's Office, a second person was killed in another storm-related incident in the Connorville-Bromide area. Details about the incident weren't immediately available.

Oklahoma isn't the only place that was impacted by the tornado which was one of several spun off by the violent weather system. The National Oceanic and Atmospheric Administration's Storm Prediction Center warned that more twisters could be spawned that will affect areas between eastern Oklahoma to central Arkansas.

A severe storm overturned and smashed at least one plane at the Salem Airport in Arkansas, located about 150 miles north of Little Rock.

Nebraska, on the other hand, had tornadoes which were accompanied by hail of up to 4.5 inches in diameter. Areas from eastern Texas to southeastern Kansas were forecast to receive hail larger than 2 inches in diameter.

The bad weather should settle in the Ohio and Tennessee valleys on Tuesday, forecasters said, while another storm system should bring storms to the area from north Texas to near St. Louis on Wednesday.