Sinkholes are most often found in seven states, including Florida, where the ground recently collapsed Thursday in Seffner. NBC's Gabe Gutierrez reports.

Authorities evacuated neighbors Friday around a sinkhole that swallowed the interior of a Florida house — apparently taking a man to his death — describing the sinkhole as "seriously unstable" and likely to keep growing.

Jeffrey Bush, 36, hasn't been heard from since he screamed as a 20-foot-deep by 20-foot-wide hole opened underneath his family's home near Tampa late Thursday. Officials and engineers were continuing their search for him Friday.

"I couldn't get him out," said Bush's brother, Jeremy, who tried to rescue him. "All I thought I could hear was him screaming for me and hollering for me, but I couldn't do nothing."

The sinkhole was still growing Friday evening, officials said, and residents of homes on both sides were evacuated.

Engineers were using three-dimensional photos of the soil and other data to figure out the best way to stop its spread, said Bill Bracken, president of an engineering firm that was called in to assist. By Friday, the hole's "safety zone" — the land around it that was considered unstable — extended 100 feet, he said at a news conference. Meanwhile, it continued to deepen and presented a significant potential for what authorities called a "sudden collapse."

The sinkhole swallowed part of the interior of the house but left the exterior remarkably intact. The only thing sticking out of the hole was a small corner of a bed's box spring. Cables from a television led down into the hole, but the TV set, along with a dresser, was nowhere to be seen.

AP Photo/Chris O'Meara Jeremy Bush, brother of Jeffrey Bush, breaks down Friday, March 1, while speaking about trying to rescue his brother.

Officials lowered equipment into the sinkhole but didn't see any sign of life.

NBC station WFLA of Tampa reported that six people were in the house when the sinkhole tore through it about 11 p.m. ET. All but Jeffrey Bush escaped.

"They heard a sound they described as a car crash emanating from the bedroom," Hillsborough County Fire Chief Ron Rogers said outside the house in Seffner. "They rushed in. All they could see was part of a mattress sticking out of the hole. Essentially, the floor of the room had opened."

The hole almost got Jeremy Bush, too. But Hillsborough County sheriff's Deputy Douglas Duvall arrived to save him, WFLA reported.

AP Photo/Chris O'Meara Engineers work Friday, March 1, in front of a home where sinkhole opened up underneath a bedroom and swallowed a man in Seffner, Fla.

Sinkholes are relatively common in Florida, but they don't always cause injury or major disruption.

Officials said they didn't immediately know whether the neighborhood near Tampa has had problems in the past, but the threat is apparently evident enough that at least two companies in Seffner advertise their expertise in "sinkhole repair."

"Florida sits on a system of caverns filled with water," Rogers said. "As that water moves up and down, it erodes those caverns, and from time to time they collapse."

Michelle Acevedo, Elizabeth Chuck and Ian Johnston of NBC News contributed to this report. Follow M. Alex Johnson on Twitter and Facebook.

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