ÃÛÑ¿´«Ã½

National Weather Service surveyed the storm's path Sunday and said the tornado caused extensive tree damage and damaged some structures. An EF-1 rating reflects a tornado of moderate intensity. 

Mark Fuchs, a hydrologist for National Weather Service, said the storm hit about four miles southwest of De Soto, with no known damage in De Soto proper.

The tornado had a length of about five miles and a maximum width of 300 yards.

There were no fatalities or injuries.

De Soto Rural Fire Protection District Chief Tom Fitzgerald said about 53 buildings were in the storm's path. Of those 53 buildings, 12 were severely damaged, he said.

Fitzgerald said the tornado started near Fletcher and ended near the intersection of Sunrise School and Hardin Roads, about three miles west of Valles Mines in southern Jefferson County.

A tornado warning was active from about 7 p.m. to 7:30 p.m. for parts of Jefferson, St. Francois and Washington counties Saturday. About 4,000 people lived within the warning area. 

The storm was "here before the warning hit," Fitzgerald said. 

"When the warning went out, we were already watching rotation," Fitzgerald said. 

The tornado lasted about 15 minutes, he said, with the worst damage along Big River Heights Road. It tore off the roof of a home on Wilson Hollow Road near Highway 21 and damaged buildings at a summer camp where no children were present, Fitzgerald said.

Saturday's tornado is at least the eighth tornado to hit the region since March. 

An EF-1 tornado hit a 6.8-mile long section of Wildwood and Chesterfield on Wednesday. 

The EF-3 tornado that tore through ÃÛÑ¿´«Ã½ and Clayton on May 16 tracked for nearly 23 miles and dissipated near Edwardsville.

At least five tornadoes touched down in the ÃÛÑ¿´«Ã½ area in March, including an EF-2 tornado that traveled from Chesterfield to Florissant.

It's been a busy year for tornadoes, Fuchs said. 

"We've had comparable years like this before, but they're not common," he said.

This story was updated Sunday afternoon to reflect the National Weather Service's confirmation of an EF-1 tornado.