A sinkhole swallowed parts of two houses on Florida's west coaston Thursday and seven nearby homes were evacuated as it continuedto expand more than six hours after being discovered, a localofficial said.

The hole in Dunedin, Florida, near Tampa, was about 60 feet wideand 50 feet deep by midday, after it pulled down a 14-foot boat anda pool, said Jeff Parks, chief of the city's fire department.

Parks said the hole measured about 25 feet wide whenfirefighters received an initial call at around 5:40 a.m. EST.

One of the affected homeowners “originally thought someone wasbreaking in his house,” Parks said.

Florida is prone to sinkholes because of its porous limestonefoundation and the cavities that are the result are a commonfeature of the state's landscape – such as springs, lakes andportions of rivers.

Sinkholes mostly occur as naturally acidic underground waterflows through and dissolves the underlying limestone. Northandcentral Florida, particularly in the Tampa area, generally aremore vulnerable than south Florida.

The sinkhole affecting residents in Dunedin on Thursday waslocated about 40 miles from one that opened in February under ahouse and swallowed a man who was sleeping in his bedroom. His bodywas never recovered.