A 4.5-magnitude earthquake happened just after 9 a.m. Wednesday.
Reports are coming in from as far away as Lawton, north to Bartlesville and south to the Red River, officials said.
The U.S. Geological Survey reported the earthquake was centered at Lake Thunderbird State Park, about six miles southeast of Norman.
"It came in loud and strong on all of our seismic stations and we are checking all of our equipment now," said Randy Keller, director at the Oklahoma Geological Survey.
Emergency responders have asked people not to call 911 unless they are injured or have serious damage to report.
Cleveland County Undersheriff Rhett Burnett said people have flooded the Cleveland County 911 center with calls.
"We're trying to keep people off 911," Burnett said.
No injuries or damage have been reported so far, said Tulsa police and fire dispatcher.
Tulsa Community College Geology Professor Claude Bolze said a 4.5 earthquake for Oklahoma is a very large quake.
The largest recorded in Oklahoma was a 5.5 magnitude - 100 times larger than Wednesday’s quake - and was felt in 1952 as far south as Austin, Texas, and north to Des Moines, Iowa, he said.
Read more from this Tulsa World article at http://www.tulsaworld.com/news/article.aspx?subjectid=11&articleid=20101013_11_0_TheNat21493
Anyone seen okie around?