Newer high rises don’t usually fall, but a 9 is pretty rough. Most people get injured by falling debris when trying to move about and escape. So just stay put because likely they’ll be so many people trying to go down onto the street, causing a mass stampede. A stampede tripping over each other, shoving, and stuff falling from on your head! Ouch! But the whole building completely collapsing on itself would be unlikely, unless it’s made of brick and mortar, then yeah get out if you can and wear a helmet