LITTLE ROCK (AP) — At least seven tornadoes touched down in Arkansas when severe storms swept through the state late Thursday and early Friday and killed seven people, though the twisters were responsible for only two of the deaths, the National Weather Service reported Monday.

Three tornadoes were confirmed in Pulaski County and one in neighboring Saline County in central Arkansas, while another hit farther west in Yell County. Tornadoes also were confirmed in Crawford and Franklin counties in western Arkansas, according to the weather service’s office in Tulsa, Okla.

The fatal tornado occurred about 2 a.m. Friday in Little Rock, knocking a tree into a home and killing a woman and her 8-year-old son in his bed. It had estimated winds of between 86 and 110 mph, said John Robinson, warning coordination meteorologist for the National Weather Service in Little Rock.

Robinson said the other five deaths were attributed to straight-line winds and marked the highest number of casualties from such winds in recent years. The sudden, violent downbursts of wind struck with hurricane force in the middle of the night.

"To have that many fatalities from straight-line winds in one episode is fairly unusual, but because it happened at night and the winds were so strong, all of those things played a factor," he said.

The storm system — the deadliest of the season — originated in Oklahoma before pushing into Arkansas and eventually into the Deep South. In total, the storm system killed at least 44 people across six states.

In Arkansas, winds knocked a tree that had been split by lightning into a home in Crystal Springs, killing an 18-month-old girl and her father as they slept. In Bald Knob, a 6-year-old boy died when the top of a tree more than 6 feet in diameter crashed through his home while he was sleeping.

Another man was killed when a tree fell on his recreational vehicle near the town of Scott. The seventh fatality was a woman in St. Francis County whose mobile home was rolled over by straight-line winds.

Many people were caught off guard when winds picked up in the middle of the night, with some winds reaching speeds higher than 70 mph, Robinson said.

"In every case of fatality, it was due to falling trees," he said. "So when you get the strong winds like that and the trees are going to fall over, the results are going to be just as deadly as if it were a tornado."

Robinson said people should prepare for straight-line winds the same way they would prepare for tornadoes. When strong winds are expected, residents should remain alert throughout the night by listening to weather radio and registering for telephone notification services.

"If they are predicting winds in the 70 to 80 mph range, this is not going to be the average severe thunder storm," he said.

Before the storm system moved into Arkansas, it spawned 21 tornadoes in Oklahoma. Two women were killed in the tiny town of Tushka, where the strongest of Oklahoma’s tornadoes hit. The tornado damaged or destroyed nearly every home along the two main streets and injured at least 25 people. The only school — a collection of buildings housing grades K-12 — was all but gone.

The storm system also killed seven people were in Alabama, six in Virginia and one in Mississippi. North Carolina’s state emergency management agency said it had reports of 23 fatalities from Saturday’s storms, but local officials confirmed only 21 deaths to The Associated Press.