The National Weather Service says the tornado that hit Moore, Okla., was a top-of-the-scale EF-5 twister with winds of at least 200 mph.
Spokeswoman Keli Pirtle said Tuesday the agency upgraded the tornado from an EF-4 on the enhanced Fujita scale to an EF-5 based on what a damage assessment team saw on the ground. The weather service uses the word "incredible" to describe the power of EF-5 storms.
The weather service says the tornado's path was 17 miles long and 1.3 miles wide.
Pirtle says Monday's twister is the first EF-5 tornado of 2013.