VALDOSTA — In the wake of tornado strikes that left at least 14 dead in South Georgia Sunday, the National Weather Service is investigating the possibility that one long-lived tornado may be to blame.

The weather service had ground teams checking damage sites in Thomas, Brooks, Berrien and Cook counties Monday, said Don Harrigan, a meteorologist with the weather service’s Tallahassee, Fla., office.

“It may have been one tornado that lifted up and touched down again two or three times,” he said, “appearing to be more than one tornado.”

The teams, which may wind up working through Tuesday, will check such things as damage to structures and trees to determine if it was a tornado or straight-line winds, and how powerful a tornado it might have been, Harrigan said.

“If all the trees are bent or blown down in the same direction, that’s consistent with straight-line winds,” whereas trees blown in every direction points toward a tornado, he said

Radar data alone cannot determine the strength of a tornado, he said.

Tornado warnings were issued for several other counties, including Lowndes, but unless the weather service receives reports of major damage, there aren’t plans to send more ground teams to investigate, Harrigan said.

While tornado warnings were issued for Echols and Clinch counties, there have been no confirmations of twisters, said Kate Guillat, a meteorologist with the weather service’s Jacksonville, Fla., office, which has responsibility for those two counties.

While there were no damage reports from Echols County, power lines and trees were blown down near Homerville, she said.

“There were no reports of funnel clouds or tornadic debris” in Echols or Clinch, Guillat said. A weather service team was checking ground damage north of those counties in Coffee and Camden counties, she said.

The Georgia Emergency Management Agency said at least 21,000 South Georgia residents were without power as of noon Monday.