The quake could prove the most powerful on state record if the 5.6 reading reported by the U.S. Geological Survey stands. The seismic monitoring agency said the quake struck at 10:53 p.m. local time Saturday (0353 GMT) and was centered about 44 mile east-northeast of Oklahoma City. It had initially reported the temblor as a 5.2 magnitude quake.
It said the quake struck near the community of Sparks -- in eastern Oklahoma between Oklahoma City and Tulsa. The temblor shook the stadium at Oklahoma State University in Stillwater near the end of the school's football game with Kansas State.
The quake was one of several to rattle the state Saturday, including a magnitude 4.7 earthquake that shook the same area early Saturday.
Michelann Ooten, a spokeswoman for the Oklahoma Department of Emergency Management, said no injuries were reported to emergency management officials and that there had been no reports of injuries.
The U.S. Geological Survey reported from Golden, Colo., on its website that it monitored a 5.6 magnitude quake at 10:53 p.m. local time Saturday and said it was centered about 44 miles east-northeast of Oklahoma City. It had initially reported the temblor as a 5.2 magnitude quake.
If the intensity of the Saturday night quake is confirmed, it would be the state's strongest on record. USGS records show that a 5.5 magnitude earthquake struck El Reno, just west of Oklahoma City, in 1952 and, before Oklahoma became a state in 1907, a quake of similar magnitude 5.5 struck in northeastern Indian Territory in 1882.
The Saturday night quake was felt as far away as Tennessee and Wisconsin, according to reports received by the USGS.
Saturday's earlier temblor, which hit at 2:12 a.m., woke people and pets as it shook an area that stretched from Texas to Missouri. Its epicenter was 6 miles north of Prague in Lincoln County, in the rolling hills about 50 miles east of Oklahoma City.
A 3.4 magnitude aftershock was reported at 2:27 a.m. from the same location, as well as a 2.7 magnitude aftershock at 2:44 a.m.
"Oh, man. I've never felt anything like that in my life," Prague City Police Department dispatcher Claudie Morton told the Tulsa World. "It was the scariest thing. I had a police officer just come in and sit down and all the sudden the walls started shaking and the windows were rattling. It felt like the roof was going to come off the police department."
Morton said the office was flooded with calls, but no one reported injuries or major damage. She said residents told her that picture frames and mirrors fell from walls and broke, drawers worked loose from dressers and objects tumbled out of cabinets.
"We do have several damaged buildings downtown, but it's just cracks and things like that," Morton said. "Nothing is destroyed or anything like that."
Oklahoma Geological Survey researcher Austin Holland told Oklahoma City television station KOTV that the earthquake and aftershocks occurred on a known fault line.
Residents in Prague and Sparks felt an intense shaking, while farther away, the quake was more of a dull rumble, he said.
"It shakes much more rapidly when you're closer to it," he said. "Because it's a large earthquake, it's going to rumble for a while."
Holland said his office received hundreds of emails from people who felt the quake. The messages came from as far as Texas, Missouri and Arkansas, he said.
Tom Foster of Oklahoma City told The Oklahoman that he slept through the earthquake but was awakened by an aftershock.
"I know we've already had several phone calls from out of state relatives wondering what happened," Foster said. "I guess it's more interesting than anything that was dangerous."
Heather Spicer of Sapulpa said the shaking woke her son and their dog.
"At first I thought an airplane had crashed nearby," she told The Oklahoman. "But now I believe it was an earthquake because the whole house just kept vibrating with what sounded like distant thunder outside."
In Muskogee, retired advertising and public relations executive Robert Rhea said he felt his home rocking for about 15 to 20 seconds.
"Oh man, it just about shook this old man out of his TV chair," said Rhea, 70, speaking with The Associated Press by telephone. He said nothing broke in his home but the state was on edge after being rattled by lesser quakes during the day.