MOSCOW — Gym class came to a halt inside the Chelyabinsk Railway Institute, and students gathered around the window, gazing at the fat white contrail that arced its way across the morning sky. A missile? A comet? A few quiet moments passed. And then, with incredible force, the windows blew in.

The scenes from Chelyabinsk, rocked by an intense shock wave when a meteor hit the Earth’s atmosphere Friday morning, offer a glimpse of an apocalyptic scenario that many have walked through mentally, and Hollywood has popularized, but scientists say has never before injured so many people.

Students at the institute crammed through a staircase thickly blanketed with glass out to the street, where hundreds stood in awe, looking at the sky. The flash came in blinding white, so bright that the vivid shadows of buildings slid swiftly and sickeningly across the ground. It burst yellow, then orange. And then there was the sound of frightened, confused people.

Around 1,200 people, 200 of them children, were injured, mostly by glass that exploded into schools and workplaces, according to Russia’s Interior Ministry. Others suffered skull trauma and broken bones. No deaths were reported. A city administrator in Chelyabinsk said that more than a million square feet of glass shattered, leaving many buildings exposed to icy cold.