First responders in Lee County, Alabama, were picking through the rubble Monday of a devastating tornado that killed at least 23 people and injured dozens more.

The tornado smashed homes and toppled power lines and a massive steel cell tower. The twister was part of a brutal system packing strong winds that also roared through parts of South Carolina, Georgia and Florida.

“The devastation is incredible,” Lee County Sheriff Jay Jones said. Jones said several people were missing, but that it was not clear whether they actually had fled the area without telling all of their concerned friends and family members.

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Here is what we know about the storm so far:

How strong was the tornado?

National Weather Service meteorologist Chris Darden categorized the storm that hit Lee County as an EF-4 tornado with winds of 170 mph cutting a .87-mile-wide path. He said the twister stretched over at least 24 miles. Darden referred to it as "a monster tornado.''

Are people injured or missing?

The numbers were not firm, but East Alabama Medical Center said it had received more than 40 patients as a result of the tornado. Some patients have also been sent to surrounding hospitals, the medical center said. Lee County Coroner Bill Harris said two people were in critical condition. Harris also said he knew of at least six people who were not accounted for, but that he had heard that the number could be as high as 20.

Harris confirmed at least three children – ages 6, 9 and 10 – had died. One was identified by her school as fourth-grader Taylor Thornton, who attended Lee-Scott Academy in Auburn.

More:'This just came on so quick': Alabama tornado kills at least 23

Was there any warning?

A warning had been issued for the deadly tornado in Lee County about 20 minutes before it hit, said Bryan Wood, a meteorologist at Assurant. And for tornadoes in general in that area, the Storm Prediction Center had given a head's-up about 90 minutes prior to touchdown.

Darden said the area had been warned of possible tornadoes days before the storm, with the most dire warning being issued 8-10 minutes before the twister hit the community of Beauregard, about 60 miles east of Montgomery.

How severe is the property damage?

Rita Smith, spokeswoman for the Lee County Emergency Management Agency, said numerous homes were destroyed or damaged in Beauregard. A massive cell tower collapsed. Smith said about 150 first responders are aiding the rescue effort and assessing damage.

Was this the deadliest tornado in years?

It was the nation's deadliest tornado outbreak in nearly six years, since May 20, 2013, when a tornado killed 24 people in Oklahoma, the Storm Prediction Center said.

Were there other tornadoes Sunday?

The National Weather Service in Tallahassee confirmed the system spawned tornadoes in Cairo, Georgia, and Leon County, Florida. Cairo Mayor Booker Gainor said the tornado struck just off the downtown area, damaging dozens of homes and businesses. There were no immediate reports of deaths or injuries, but Gainor said several residents had been trapped in their damaged homes. In Florida, the Leon County Sheriff’s Office said at least 10 homes were damaged.

Contributing: Grace Pateras, Tallahassee Democrat; Alyssia Pacheco, Montgomery Advertiser