More sinkholes reported in Florida

SPRING HILL, Florida (CNN) -- Emergency officials continued to investigate more reports of Florida sinkholes on Saturday, two days after the earth dropped some 100 feet in areas of a residential town north of Tampa.

"We seem to be ... the epicenter of sinkholes," said Bill Appleby, emergency management director for Hernando County.

Appleby said they have confirmed 18 sinkholes hit the area, almost all on Thursday. On Saturday, officials were investigating at least two more reports. They expect more calls throughout the weekend.

No one was hurt in the spate of sinking holes, but an emergency worker narrowly escaped injury when the earth sank beneath him while he was on a backhoe clearing debris.

Appleby said the largest holes, which sank near a water retention area, measured between 50 and 100 feet deep. He explained that the sinkholes open "very suddenly, without any warning whatsoever."

Sinkholes are not uncommon in this town, about four miles inland from the Gulf of Mexico and about 45 miles north of Tampa.

"We normally get two or three reports a week," Appleby said. "It is unusual to have this many so close."

The sinkholes affected a 15-to-16 block residential area, Appleby said.

One house was evacuated after it suffered extensive damage as a result of the ground sinking.

Appleby said Florida law requires insurance carriers to cover sinkhole damage to structures, but not to property.

The area had received heavy rains over the past few days, measuring over four inches in some areas. The rains, combined with an ongoing drought, most likely caused the ground to sink.