At Will Rogers World Airport southwest of Oklahoma City, passengers were directed into underground tunnels and inbound and outbound flights were canceled.

NPR: 2 Dead When Tornado Hits Oklahoma City Area

Oklahoma City's Will Rogers World Airport was evacuated over the threat from the approaching tornado, and travelers were sheltered in the airport's basement at the height of the storm, authorities said.

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The storm system swatted down power lines and uprooted trees, flicked big rigs on their sides and yanked off part of the terminal roof at Oklahoma City's Will Rogers World Airport, where some 1, 500 area residents had taken shelter in a tunnel.

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