PHILADELPHIA (CBS) — The tornado that ripped through Moore, Oklahoma has been preliminarily rated as an EF-4, the second strongest possible tornado, by the National Weather Service.

The storm was on the ground for about 20 miles on Monday, and at least 24 people have been killed, including seven children.

Initial reports suggested that over 50 people had been killed, but the Oklahoma medical examiner pulled back the number earlier this morning after learning of duplicate reports. However, the death toll is still expected to rise.

Softball and baseball sized hail in addition to 200 mile-per-hour winds left more than 236 people in local area hospitals. The tornado lifted from the ground at 3:36 p.m. after being on the ground for nearly 40 minutes.

The path of the mile-and-a-half-wide twister included the towns of Newcastle, Moore, and southern portions of Oklahoma City, with Moore being the most damaged area. Moore has a population of 56,000 people, and this is the fourth tornado to occur there since 1998.

Moore was hit with one of the most damaging tornadoes ever in 1999. The F-5 tore through more than 600 homes and 100 businesses at the time, and a couple schools were also hit, but the students were not inside at the time. The May 3, 1999 twister followed a similar path to Monday’s storm. Seventy-four tornadoes were reported on that day across portions of Kansas and Oklahoma. Forty-six people died, and more than 800 were injured in the storm, which caused around $1.5 billion in damages.

The fastest wind speed ever recorded in the continental U.S. was reported in one of the May 3 storms during the 1999 Tornado Outbreak, clocking in at 318 miles-per-hour.

More severe weather is on the way for the Great Plains, but Moore is not expected to be in the direct path.

A tornado watch has already been issued for portions of northern Texas and extreme southern Oklahoma, including the Dallas-Fort Worth and Waco areas, with more tornadoes and large hail expected.

Our thoughts and prayers are with those who were affected. You can help by texting REDCROSS to 90999 to donate $10 to tornado victims.

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