Building collapses are rare, but there are warning signs to look for

HOUSTON, Texas (KTRK) -- As Houstonians watch rescue workers search through the rubble after a multi-story building partially collapsed in southern Florida's Miami-Dade County, many share the same concern.

"Children and elderly people - that's the first thing that comes to my mind," said Houstonian Jawan Barnes.

At least three people have died and up to 99 are missing, according to Florida authorities. Champlain Tower South -- a 12-story residential condo in the beachside town of Surfside, about six miles north of Miami Beach -- has 136 units, and 55 have collapsed, officials said.

During an evening briefing on Thursday, officials said 102 people have been identified and declared safe.

As search efforts continue for residents inside a partially collapsed building, Miami-Dade Mayor says at least 102 people have been declared safe, 3 were killed and 99 are unaccounted.

Joseph Colaco, a University of Houston architecture professor, said collapses like the one in Florida are rare. He would know. Colaco is an engineer responsible for developing much of Houston's impressive skyline.

"We've gone through Hurricane Harvey, which was a big flood event, Hurricane Ike, and nothing has happened," he said.

Colaco said high-rise buildings aren't necessarily more dangerous than single-story buildings, because they're usually built by large, experienced firms. But when a collapse does happen, there are often warning signs.

"Before there's a collapse, you will see things happen," he said. "You either see a slab deflecting downward or you will see a crack open up in a column."

It's important to note, hairline cracks are normal, but if you do start to see bigger ones popping up, call your property manager.

"If you can put a point inside the crack, then you start to worry about it," said Colaco.