The building had been on fire for hours at that point with no water pressure to run the sprinklers or allow firefighters to effectively combat it. It was decided to stop efforts to save the building as it was presumed the integrity of the structure was damaged beyond repair.
As for the reporters announcing it collapsing early, its doubtful that it was anything but one of many mistakes reporters made live on air hours into an exhausting day of chaos. Maybe that had been told the building was going to collapse at any minute or maybe they had been told efforts to stop collapse had ceased and an assumption was made by the crew on the ground it had already fell. As I recall it was the BBC that said it fell before it actually did, so the idea of a foreign news outlet being in on a false flag conspiracy is just too ridiculous to be believable over something such as an exhausted reporter misspeaking in the middle of an emotionally overwhelming day.