British officials said at least 12 people were killed when a massive inferno tore through a 27-story residential building in West London early Wednesday morning. A police spokesman said that number was expected to rise. The blaze erupted just before 1 a.m. local time, with residents thought to be trapped inside as at least 250 firefighters struggled to contain the flames. Authorities said the fire at Grenfell Tower on the Lancaster West Estate in west London reached from the second story all the way to the top, with 45 fire engines dispatched to the scene. More than 70 people were taken to hospitals, and the BBC reports at least 20 are in critical condition. Images from the scene showed the entire high-rise engulfed in flames, with witnesses saying they could see debris falling from the building and hear parts of it collapsing. Others said they could see residents on the upper stories shining flashlights in a plea for help, while other residents were spotted tying sheets together to form ropes. There were some eyewitness accounts suggesting that people had jumped or even thrown children from the building but that has not been confirmed. The cause of the fire is not yet known.