Death toll reaches 9 in Fla. condo collapse

He noted that the pancake collapse of the building has made it difficult to find survivors.

Rescuers also were using a microwave radar device developed by NASA's Jet Propulsion Lab and the Department of Homeland Security that "sees" through up to 8 inches of solid concrete, according to Adrian Garulay, CEO of Spec Ops Group, which sells them, AP reported.

The device can detect human breathing and heartbeats and was being used Sunday by a seven-member search-and-rescue team from Mexico's Jewish community.

Florida Governor Ron DeSantis praised the search teams as being "some of the best in the business".

"I'd hope that none of these things would ever happen anywhere, but if something like this happens, the people you would want are Miami-Dade search and rescue," DeSantis said during a news conference Sunday. "These teams have gone all over the world. These are the people that you want."

The government of Israel said it was sending a team of engineering and rescue specialists to aid the search. Israeli media have reported that some 20 citizens of that country were believed among the missing.

Another 22 people unaccounted for were from Argentina, Venezuela, Uruguay and Paraguay, including relatives of Paraguayan first lady Silvana de Abdo Beníte.

Albert Aguero, a New Jersey man in Florida for the weekend with his wife and two children, was sleeping on the 11th floor of the Champlain Towers South early Thursday.

Aguero was awakened by swaying chandeliers and a power outage and initially thought lightning had hit the building, he told NBC News. He walked to the balcony and saw a gray cloud hovering.

"I looked to my left and half of the apartment is gone, look forward and the elevator shaft is there, and there's no elevator; it's just two holes," Aguero told NBC South Florida.

"We got to the stairwell, and when we opened the door, that's when everything really hit, because half the wall to the stairwell was missing. It was kind of open-air stairs, so now we're just racing down as fast as possible," Aguero said.

Ai Heping in New York, Reuters and The Associated Press contributed to this story.