At 6:48 pm CST (00:48 UTC), a large, violent wedge tornado – a tornado that is wider than the distance from ground to cloud base – touched down near the Red River, along the Texas-Oklahoma border.
It crossed through Jefferson and Love counties before entering Carter County where it proceeded to slam into Lone Grove.
The tornado dissipated at 7:43 pm CST (01:43 UTC) after remaining on the ground for nearly an hour and traveling an estimated 35 mi (56 km).
After an assessment by the National Weather Service office in Norman, Oklahoma, the tornado was rated as an EF4 on the Enhanced Fujita Scale with winds reaching an estimated 170 mph (270 km/h).

The Lone Grove tornado was the deadliest to strike Oklahoma since May 3, 1999, and the strongest tornado during the month of February in Oklahoma since 1950.
The previous strongest were two F3 tornadoes which touched down on February 17, 1961.

The tornado destroyed businesses and residences across a swath over 0.5 mi (0.80 km) wide and 35 mi (56 km) long.
In Lone Grove alone, buildings were thrown off their slabs and the local chamber of commerce office was flattened.
The tornado destroyed a furniture store, and shattered the glass lobby of the local UPS building.
The destruction of a mobile home park containing 40 homes left close to 100 people homeless.
One mobile home was thrown 100 yd (91 m) from its foundation.
A total of 114 residences were destroyed in Lone Grove.

To the east of Lone Grove, the area north of Ardmore was also hard hit.
Several buildings, including those of the Beaver Academy and the Ardmore Adventist Academy, were destroyed.
Although damage centered on the Ardmore Academy gymnasium, most of the campus was considered a total loss.
In Ardmore, eight homes were destroyed and another 20 sustained damage.

Eight people were confirmed dead as a result of the tornado.
Seven of these fatalities were in the town of Lone Grove; most were determined to have been caused by "blunt-force trauma to the head".
Three of the victims were found inside their homes and two were found outside.
A victim found in an open field was reportedly picked up and thrown by the tornado, and died on impact with the ground.
One victim was crushed when a pickup truck fell on him; similarly, a truck driver died after being pinned under his vehicle on Interstate 35.
Two other victims, the parents of a 13-year-old girl, were killed when the tornado picked the three of them out of their home and threw them 400 ft (120 m).
Three people were rescued after being trapped in the ruins of their home for almost a day.
Officials stated that 10 to 15 people remained unaccounted for on the night of February 12 but they were presumed to have left the area.
An additional 46 people were injured.
Total monetary damages from the tornado were estimated at $3 million.
At 6:48 pm CST (00:48 UTC), a large, violent wedge tornado – a tornado that is wider than the distance from ground to cloud base – touched down near the Red River, along the Texas-Oklahoma border. It crossed through Jefferson and Love counties before entering Carter County where it proceeded to slam into Lone Grove. The tornado dissipated at 7:43 pm CST (01:43 UTC) after remaining on the ground for nearly an hour and traveling an estimated 35 mi (56 km). After an assessment by the National Weather Service office in Norman, Oklahoma, the tornado was rated as an EF4 on the Enhanced Fujita Scale with winds reaching an estimated 170 mph (270 km/h).
The Lone Grove tornado was the deadliest to strike Oklahoma since May 3, 1999, and the strongest tornado during the month of February in Oklahoma since 1950. The previous strongest were two F3 tornadoes which touched down on February 17, 1961.
The tornado destroyed businesses and residences across a swath over 0.5 mi (0.80 km) wide and 35 mi (56 km) long. In Lone Grove alone, buildings were thrown off their slabs and the local chamber of commerce office was flattened. The tornado destroyed a furniture store, and shattered the glass lobby of the local UPS building. The destruction of a mobile home park containing 40 homes left close to 100 people homeless. One mobile home was thrown 100 yd (91 m) from its foundation. A total of 114 residences were destroyed in Lone Grove.
To the east of Lone Grove, the area north of Ardmore was also hard hit. Several buildings, including those of the Beaver Academy and the Ardmore Adventist Academy, were destroyed. Although damage centered on the Ardmore Academy gymnasium, most of the campus was considered a total loss. In Ardmore, eight homes were destroyed and another 20 sustained damage.
Eight people were confirmed dead as a result of the tornado. Seven of these fatalities were in the town of Lone Grove; most were determined to have been caused by "blunt-force trauma to the head". Three of the victims were found inside their homes and two were found outside. A victim found in an open field was reportedly picked up and thrown by the tornado, and died on impact with the ground. One victim was crushed when a pickup truck fell on him; similarly, a truck driver died after being pinned under his vehicle on Interstate 35. Two other victims, the parents of a 13-year-old girl, were killed when the tornado picked the three of them out of their home and threw them 400 ft (120 m). Three people were rescued after being trapped in the ruins of their home for almost a day. Officials stated that 10 to 15 people remained unaccounted for on the night of February 12 but they were presumed to have left the area. An additional 46 people were injured. Total monetary damages from the tornado were estimated at $3 million.
Tornado outbreak of February 10–11, 2009