The central US state of Oklahoma was rattled by a 5.6 magnitude earthquake felt as far away as Texas, the strongest ever to strike the area, followed by several smaller shakers on Sunday.

After initially rating the quake at 5.2, the US Geological Survey upgraded the strength of Saturday's seismic event -- the biggest in a series of more than 20 quakes and aftershocks to hit a zone more accustomed to tornadoes.

The epicenter of the record tremor, which occurred at 10:53 pm Saturday (0353 GMT Sunday), was located just six kilometers (four miles) east of the town of Sparks at a shallow depth of only five kilometers.

Lincoln County Emergency Management said there had been significant damage to buildings as chimneys collapsed through the roofs of homes and several roads were ruptured.

State officials told local media there were no injuries reported, but residents said they were frightened.

"My wife had just stepped out of the truck when the ground shook beneath her feet and she jumped up," JL Gilbert, owner of the Sparks Vineyard and Winery, told AFP, estimating that the tremor lasted for around 30 seconds.

"It's the biggest jolt we ever had and I remember the last big one in the 1950s. We're used to tornadoes but you can see them coming but this earthquake was a surprise," said the 63-year-old, noting that local houses had been damaged but he was unaware of any major injuries.

"My favorite old clock fell off the wall so I had to repair that, but no wine bottles were smashed. I would have been really upset if that had happened," he added.

Local authorities issued guidance online, advising people to "Drop, Cover, and Hold On!" if other aftershocks hit the area.

Oklahoma City is 72 kilometers southwest from the epicenter of the quake. A strong jolt was also felt in Kansas City, more than 350 miles away.

According to USGS, the strongest earthquake previously recorded in Oklahoma occurred on April 9, 1952 and measured 5.5 in magnitude.

Local television station KJRH reported that a crowd of nearly 59,000 was on its way out of Oklahoma State's Boone Pickens Stadium when the earthquake hit, and players were in the locker rooms beneath the stands.

"Everybody was looking around, and no one had any idea," Oklahoma State quarterback Brandon Weeden was quoted as saying. "We thought the people above us were doing something. I've never felt one, so that was a first."

Saturday's quake was only slightly weaker than a surprise 5.8 magnitude tremor that struck the US east coast on August 24, causing a small crack near the top of the iconic Washington Monument in the US capital.