The National Weather Service has upgraded a tornado that tore through central Oklahoma last week to EF5, the highest rating given to tornadoes.

The weather service in Norman said Wednesday the May 24 tornado that started in Binger and traveled 75 miles to Guthrie had winds in excess of 210 mph in some parts.

Ten people died in the storm, which traveled across four counties.

Meteorologists from the weather service had been investigating the storm and its damage path for the past week, said Rick Smith, warning coordination meteorologist for the weather service in Norman.