Transcript for What we know about the Miami building collapse
Ran for our lives. Nothing but big white cloud of dust. It was brutal.pit just felt like an earthquake. Reporter: In the quiet hours of the night, the unthinkable happened. This 136-unit building near Miami beach came crashing down and security video capturing it all. This building right here is gone. The whole back side of it, everything to the beach. It collapsed. 12 to 13 stories. Reporter: Many inside running down to the street. Gabe feels lucky to be alive. He moved into one of the condos 11 months ago. I did not think it was real. I thought it was a dream. There were a lot of rumbling noises going on. The second was more intense. I prayed that everybody would make it out safe. Reporter: First responders rushed to the scene searching through the rubble for any signs of life. Hearing a voice cry don't leave me, discovering this young boy, one of at least two people pulled from the rubble. A massive search and rescue is underway and we will do everything we can do. Reporter: Here is the building before the collapse and then after. A scene more reminiscent of Syria than south Florida, the scope of devastation revealed once the sun came up. You don't see buildings falling down in America. Here we had a building fall down. Reporter: The desperate search continues for those that did not make it out. Miami-dade fire rescue searching under the pancaked building. Another body was recovered from the wreckage tonight. First responders driving in large equipment to remove debris and help in the search. So far, three people dead and with 99 still missing, families and friends are franticly looking for loved ones. They haven't been answering their phone. Reporter: My colleague spoke with a woman who believes her husband, Brad and brother-in-law were in the complex when it collapsed. The family was in the process of moving. He wanted to live such a long live. I would never think anything like this would happen and saw that rubble. Now there is no way he will be alive in that. Reporter: Nicholas Fernandez is searching for close friends, making frequent calls. Family. Having at least a hope of maybe the rescue team will hear the cell phone and have a clue. Reporter: Among the missing, dozens of South American countries including -- so far 102 people have been accounted for. Families and friends have flocked to a reunionification center blocks from the collapse. What is that process like to try to reunite those folks? We have chaplains. We have different religious we have different types of people. We have the red cross. We have everybody that can help these individuals. They are desperate to know about their family members if they survive the collapse. So we have every asset that we have learned through the years to be able to employ to help these individuals in their worst moment. Reporter: The here is scale of the damage pushing the president to make a vow. I say to the people of Florida whatever help you want the federal government can we are waiting. Just ask us. We will be there. We will be there. Reporter: The Champlain towers south, six miles north of Miami. 12 stories with 136 units housing a mix of year-round residents, snowbirds and part-time renters and for decades stood against hurricane force winds. The catastrophe happening shortly after 1:00 A.M. The town becoming choked in dust and smoke. The residential tower suffered a partial pancake collapse while many ofhe residents inside were sleeping and in mere seconds 55 units were reduced to rubble and survivors saying that it sounded like thunder. The first responders starting to arrive on the scene shortly after receiving the call at 1:38 more than 80 fire trucks dispatched, making their way into the chaos. I have never seen so many ambulances and police all at once. Reporter: Residents on balconies waving down the rescue teams. We have people standing upstairs that need to be evacuated. Reporter: 35 survivors were pulled from the building and the urgent and delicate search inside began. Not knowing how many were in the building at the time. We are not sure who is there and not Reporter: Walls ripped away, bunk beds moments before residents were sleeping. The part of the complex standing with precarious concrete chunks, dangling wires and fires complicating rescue efforts. Search dogs brought in to go where rescuers couldn't. We had the dogs out there this morning Reporter: A trauma center assembling a staff and supplies to help. Part of the rescue teams included trauma surgeons and a team of doctors packing up gear to take on to the scene, ready for any type of emergency. Often they need to do a field amputation to get someone out of a building or a car whenever they are trapped. They slowly trickle in over time. Reporter: Even though it is very rare, this is not the first time that buildings collapsed in the nation. 2015 an apartment building in New York City toppled due to a gas explosion leaving two dead and 19 injured. The most fatal building collapse occurred in Missouri in 1981 when a high at collapsedue to a structural failure leaving 114 dead and 200 injured. But what caused this residential tower to fall? No signs of a sink hole or gas explosion. It is going to be a long and exhaustive search for the cause of the catastrophe. The enormity of it was shocking and they will be looking in the field at the orientation of the debris and the way that it is broken. The way that the parts are stacked up against each other. You can use a lot of that material to really try to recreate how the initiation of the collapse occurred. So, it is a bit like taking a jigsaw puzzle in a pile and putting it back together again. Reporter: One commissioner said the towers were scrutinized in recent years and it was up for the 40-year recertification and construction of a nearby building led to issues with the towers garage. There were cracks from that project. They were just patched up. Nothing based on my understanding to the magnitude that would indicate there was a structural problem that could result in something so catastrophic. An inspector was on scene as recently as yesterday. Other clues and a 2020 study out of Florida international university finding land in the Champlain towers area was sinking at an alarming rate in the 1990s. We saw the building moved 20 to 30 years ago and whatever caused the collapse started many years ago. Reporter: Meanwhile the search for the missing continues. First responders pivoting from inside the building to underneath the rubble. Rescue teams are hoping for pockets inside of the rubble where they might find survivors. They have been working in teams of 10 to 12. Working until exhausted. Every time we reach parts of the structure, we get debris that falls on us. Reporter: The moves precise and methodical to prevent further tragedy. They assess the structure every hour, every time there is a weather shift and place seismic devices on the building. First responders heard sounds of banging, so far no voices. But nobody is giving up hope yet. Currently right now at this hour that team is in there trying to find survivors. We hope that we are praying that the sounds that we hear and equipment that we are survivors in there in a pocket under all of the rubble that is there. That is what we can hope for. Thanks to Stephanie.
This transcript has been automatically generated and may not be 100% accurate.