Transcript for Multiple fatalities in massive London high-rise fire
that horrific scene in London. There it is right there, that London high-rise active search and rescue operation right now. Horrific and scary scene at that, George. Deadly fire erupted as hundreds of people were sleeping inside. Witnesses say they saw people dangling from the windows and families were trying to escape. I know. When you watch these scenes like this, so hard and the smoke is stretching for miles. Officials calling this an unprecedented incident. ABC's James Longman has been on the scene for us all night. Good morning, James. Reporter: Good morning, robin. I'm about 150 yards away from the building. As you can see it's still smoldering. Pockets of fire still ablaze after 11 hours and there's concern this morning about the stability of that building. We understand so far six fatalities have been confirmed but that number is likely to rise and there are still a number of elderly and children missing. This has been a catastrophic fire. Balls of fire bursting from the windows. Crazy happening. Reporter: Panicked calls for help from inside. Let me out. Reporter: And frantic acts to break away. Residents Dean dropping down makeshift ropes trying to estate. This guy is sending a rope. Don't do it. Reporter: More than 200 firefighters battling the raging inferno in this apartment building at least 24 floors high. We have now taken over 50 patients to hospitals across London. Reporter: Countless residents trapped inside the high-rise in the heart of London throughout the night. We could hear people screaming help me. Reporter: One partially blind elderly man trapped on the 11th floor. Cameras capturing him terrified as he waits for help and still others missing. Your brother is trapped. We've gone around the hospital. Reporter: Hundreds of firefighters struggle to take down the blaze but the building is so tall, much of the fire is impossible to contain. Please move back, everybody. Reporter: Firefighters pushing bystanders back from the scene. From here you can see debris falling off the building and they've moved the police cordon back because there's real fears it may collapse. Thick black smoke towering high and far throughout the city. People were still sleeping on the higher floors and didn't have a clue what wau going on. I'm not sure if half of them even got out. Reporter: There's been no mention of terrorism as the cause of this so far, but no one really knows what started this fire but a number of issues around the safety of this building going back years so a lot of questions for the investigation going forward.
This transcript has been automatically generated and may not be 100% accurate.