ELKTON, Fla. - Straight-line winds caused the partial collapse of two barns in the 6400 block of CR 305, south of SR 207, officials say.
One tree was also knocked down and power lines were bent, the National Weather Service reports.
The storm was in the southwest corner of St. Johns County and is now offshore of St. Augustine.
According to the NWS, the weather event was a microburst, producing straight-line winds estimated at 70 to 80 miles per hour. Damage was not noted upstream or downstream from the damaged barns.
"Everything was strewn in one direction -- all the poles and the barns and some of the trees were all in one direction, which is very indicative of straight-line winds," said NWS meteorologist in charge Scott Cordero.
Cordero said a warning was not issued in the Elkton area due to the quick nature of microbursts.
"We had a warning out for the neighboring county in Clay County, and no, we did not have a warning out for this particular area," Cordero said. "What happened in a microburst environment is the thunderstorm goes up so fast (and) it comes down so fast that sometimes it goes within the frame of the radar scan of six minutes apart and that's probably what happened here in this case."
No injuries were reported as a result of the storm, according to the St. Johns County Sheriff's Office.
Witnesses were amazed at the speed at which the microburst occurred.
"I couldn't believe it flattened the barns like that. They're more sturdy than a lot of things, but I was shocked," said Samantha Goodson, who went into the bathroom with her kids during the storm.
"It started hailing and then the winds picked up and it got super-loud, but it wasn't like the people describe as a train. It was just screaming wind," said Bobby Cain.