As many as 10,000 people reported feeling tremors across much of Oklahoma, except the panhandle, and North Texas, said a seismologist for the U.S. Geological Survey.
The reports were made on the USGS website, earthquake.usgs.gov, said Earle, of the USGS Earthquake Center in Golden, Colo.
Earle said Wednesday's quake was "deeply buried with no surface expression," but no major damage was reported anywhere by 10 a.m.
Earlier reports stated the quake registered 4.5, but that was downgraded later to 4.3, Earle said.
There were no immediate reports of damage or injury, but officials at the National Earthquake Information Center said some minor damage might be expected.
"At 4.3 it was nothing like the 7.0 that hit Haiti" in January, Earle said. "You're not going to see any structural damage, but there definitely have been a number of people who were shaken."
North Texans confirmed the seismic rumbling.
Parker County Sheriff Larry Fowler said his office received tremor reports from around Brock, and another man reported the walls shaking west of Aledo.
"Our office just shook for 10 seconds or so," said Bobby Johnson of Sacramento Energy Resources in Aledo at 9:16 a.m.
The shaking was "not enough to knock things off the walls," Johnson said, "but it visibly shook pictures and computer monitors and chairs, etc."
Johnson said his office is near the intersection of Old Annetta Road and Farm Road 5 in Aledo.
"We thought it could have been something else because we're pretty close to a freight train, but we didn't see it or hear it coming," Johnson said. "It was something that was just obvious when we realized it."
Johnson is no stranger to aftershocks.
"I used to live in Long Beach, Calif., where I would occasionally feel aftershocks from earthquakes," he said.
Tonya Hicks Williams, who was at her Weatherford home making jewelry, said she could feel the shaking in her body at 9:05 a.m.
"I thought I was crazy until my Chihuahua started barking and running in circles," Williams said.
Her wooden roof started to shake so much, Williams said she thought it was going to collapse.
Williams said that after it stopped, she noticed what she thinks might be some damage to the roof. She said she has called her husband to come home and investigate.