A 12-story condo building on the beachfront in Surfside, Fla., partially collapsed early Thursday morning, killing at least 18 people. More than 145 others remained unaccounted for on Friday, more than a week after the building collapsed.

Investigators say it is too early to know what caused the building’s collapse. A Washington Post examination of videos, photos and audio shows the building collapsed in less than 30 seconds.

The building

Located at the corner of Collins Avenue and 88th Street, Champlain Towers South contained 136 condo residences. Completed in 1981, the building boasted luxury amenities and beachfront access.

The collapse

Adriana Sarmiento told ABC7 Chicago she and her husband were swimming in the pool at Bluegreen Vacations Solara Surfside Resort not long after 1 a.m. when they heard a noise. The two got out of the pool, which is located directly across from the entrance to Champlain Towers South’s parking garage, and Sarmiento began filming.

The video, first published to Sarmiento’s TikTok account on June 29, appears to show water running from the ceiling of the garage and a small pile of debris on the garage’s floor at approximately 1:18 a.m. This video comes as a Washington Post examination raised additional questions about whether existing damage to a deck in the pool area contributed to the disaster.

(@adrianitacastillero via Storyful)

Two minutes later, at approximately 1:20 a.m., according to time codes provided by website Broadcastify, a dispatcher with Miami-Dade County Fire and Rescue calls for Engine 76 to respond to a “Jefferson alarm ringing 87th and Collins Ave.” Moments later, she clarifies the destination to “Champlain Towers South.”

According to EMS audio, the building collapses between 1:24 and 1:25 a.m., but Engine 76 is already en route.

A video filmed roughly 300 feet away captures the moment of collapse. First published on Twitter by journalist Andy Slater, the video appears to show the northern section of the building fold onto itself first, quickly followed by the ocean-facing eastern tower.

(Andy Slater)

A security camera video from resident Rosie Santana’s unit shows debris beginning to fall from above. The video feed cuts just over 13 seconds later, when audio suggests the building begins to collapse.

Within 30 seconds, nearly half of the building had collapsed, and plumes of smoke enveloped the vast majority of the remaining structure. Miami-Dade Assistant Fire Chief Ray Jadallah told reporters that 55 units in the building were affected.

(Miami-Dade Fire Rescue)

A first responder with Engine 76 called in at 1:29 a.m., according to Broadcastify time codes. “This is going to be an entire building,” he said, counting the floors. “One, two, three, four, five … 12 or 13 stories. Um, s‐‐-.” He paused before continuing. “Most of the building is gone.”

The aftermath

(@fdpdaction via Storyful)

Videos and photos reveal a hectic next several hours, as more than 80 emergency response vehicles crowded the streets surrounding the building.

In radio feeds, more unsettling descriptions of the scene came through as first responders continued to arrive. One warned arriving vehicles to park at a light near the incident site. “We need a containment area. This building does not look stable.” Others noted that survivors were stuck on their balconies because there was no exit route through the building’s interior. The responder from Engine 76 compared the scene to the aftermath of the 9/11 attack. “This, this is nothing, I mean. It almost resembles the Trade Center.”

Just seconds later, “76” called in again and said some people had heard what sounded like a bomb. He did not provide any more details.

Emergency responders climbed piles of rubble that in some places appeared to be more than six feet high, as furniture and air-conditioning units dangled above them from the edge of the building.

(Michael Watson)

Actor Jamal Akakpo had been staying in a hotel next to Champlain Towers South. He posted videos from the scene showing emergency responders and a pile of rubble. One man who claimed to have been in the building when it started to collapse said the event “felt like an earthquake.”

(Jamal Akakpo)

More than 12 hours later, the scene continued to smolder as rescuers searched for missing people. In a video shared by Miami-Dade Fire Rescue, firefighters waded through the flooded parking garage beneath the towers searching for survivors.

(Miami-Dade Fire Rescue)

Timothy Bella, Tim Elfrink, Karly Domb Sadof and Derek Hawkins contributed to this report.