(CNN) -

The ground just swallowed him up.

A Florida man lying in bed fell into a sinkhole that opened suddenly beneath the bedroom of his suburban Tampa home, calling out to his brother for help as he fell, a fire department spokeswoman said Friday.

Five other people, including a 2-year-old child, escaped from the home. Rescuers had to pull the man's brother away from the edge of the sinkhole as it ate away at the ground under the home, according to Jessica Damico, a spokeswoman for the Hillsborough County Fire Department.

The man was presumed dead, she said, after monitoring equipment lowered by engineers detected no signs of life.

But rescuers can't go into the hole to check -- it's too dangerous. Authorities say they worry the hole is still spreading and the house could collapse at any time.

Authorities evacuated nearby homes as well -- in case the hole keeps growing, she said.

The sinkhole is naturally ocurring and appears to be about 100 feet across, based on estimates made by engineers using radar, and it may be as deep as 50 feet, authorities say. It's not visible except inside the home.

Rescue crews were waiting Friday morning for engineers with more sophisticated equipment to examine the sinkhole.

Sinkholes are common in Florida, according to the Florida Department of Environmental Protection. The state lies on bedrock made of limestone or other carbonate rock that can be eaten away by acidic groundwater, forming voids that collapse when the rock can no longer support the weight of what's above it.