What to Know About the Building Collapse in Surfside, Fla.

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A search-and-rescue effort involving firefighters, police officers and search dogs was underway on Thursday after a high-rise residential building just north of Miami Beach partially collapsed.

At least one person was killed, the police said. Florida’s governor said that, given the destruction, “we are bracing for some bad news.”

Here’s what we know about the scene.

About half of the 136 units in the 12-story tower had collapsed, according to Daniella Levine Cava, the mayor of Miami-Dade County, Fla. “We’re going to do everything we can possibly do to identify and rescue those who have been trapped in the rubble,” she said at a news conference Thursday morning.

The beachside building, at 8777 Collins Avenue, is called Champlain Towers South and was built in 1981, according to city property records. It has 136 units, according to to the Miami-Dade property appraiser.

Fiorella Terenzi, an associate professor at Florida International University who lives in a neighboring building, Champlain Towers East, said she woke up early Thursday to a loud noise.

The sound “was like a big thump all of a sudden,” she said. At first she thought it was thunder but then started to hear sirens. When she left the building, dust was everywhere.

“I could see that half of the building of the Champlain Towers South was collapsed like a sandwich,” said Ms. Terenzi, 59, who has lived in the east tower since 2000. “It really was a shocking view.”

The police have confirmed one death. “We are bracing for some bad news, just given the destruction that we’re seeing,” Gov. Ron DeSantis of Florida told reporters.

About 35 people were rescued from the building, and two were pulled from the rubble, Ray Jadallah, a Miami-Dade Fire Rescue assistant fire chief, said at the news conference.

“A number of people” were rushed to nearby hospitals from the rubble of the collapsed building, a police spokesman said. At least two people were in critical condition, according to a spokesman for Aventura Hospital and Medical Center.

Chief Jadallah said it was not clear how many people were still missing. Charles Burkett, the mayor of Surfside, told the “Today” show on NBC that dogs had been searching for people trapped under the rubble since 2 a.m.

“Just tragically there haven’t been any hits from the dogs, and that’s a great disappointment,” he said. “Apparently when the building came down, it pancaked. So there’s just not a lot of voids that they’re finding or seeing from the outside.”

He said 15 families were being relocated to hotels.

Mr. Burkett said that it was also unclear how stable the rest of the building was. “We don’t know if the rest of that build is going to come down,” he said. The authorities said it was not immediately clear what caused the building to collapse.

Christine Hauser and Derrick Bryson Taylor contributed reporting.