CAMBRIDGE — Students at MIT described the tense atmosphere that descended on campus as soon as they received an emergency text message informing them that a gunman might be on the school grounds — a report that turned out to be a hoax.

“It’s definitely unsettling,” Will Talbott, 29, a graduate student, said on Sunday. “Even though it was a hoax, it gives you more of a sense of what it would be like to have a school shooting — or any kind of shooting — happen here.”