EAST LANSING, Mich. — Jane Nodland had just arrived at the Michigan State University Union, a four-story gathering space with meeting rooms, a restaurant and a small store, to do homework on Monday night with her boyfriend.

Then she heard three gunshots, dove into a corner with her boyfriend and hid in terror before they ran to the exit and dashed out of the building with the other students. No one was yelling or screaming, she said, and it sounded like a stampede.

“I thought I was going to die,” Ms. Nodland, 22, a senior nursing major, said. “It sounded like he was right there.”

Ms. Nodland was one of many students and East Lansing residents who waited anxiously in dorms, restaurants and other places in the hours before the university police said early Tuesday that the 43-year-old gunman had died from a self-inflicted gunshot wound. For much of the night, they had few details about where he was or what he was doing.

“Run, Hide, Fight,” an 8:31 p.m. email told students and faculty about shots being fired “on or near” the East Lansing, Mich., campus. “Run means evacuate away from danger if you can do so safely, Hide means to secure-in-place, and Fight means protect yourself if no other option.”

Elena Tucker, 21, was in her apartment, a few hundred feet from campus, when that message came in. She also got a call from her mother in Ann Arbor, Mich. and texts from several friends. Yes, she was safe, she told them.

Still, as hundreds of police officers searched for the gunman and rumors flew about his location, she and her friends didn’t feel entirely secure sitting in her living room and watching the news and listening to police scanners.

“Everyone was texting their parents constantly,” said Ms. Tucker, who takes classes in Berkey Hall, one of the buildings where the gunman opened fire.

Others were trapped on campus.

Julian Alonso, a Michigan State University freshman, said that he had left his dormitory on Monday evening to buy a snack at a 7-Eleven, and returned a few minutes later to find at least 10 police cars a block away.

“I covered the door with my roommate’s bed and I turned off the lights,” he said at the time. “I’m keeping myself hidden in the closet.”

Marcus Wolff, 20, said on Tuesday that his usual Monday night volleyball game in a campus gym had been cut short by reports of a gunman on the loose. Minutes later, the gym was put under a lockdown and the lights were turned off.

“That was probably the scariest moment of it all,” said Mr. Wolff, an electrical engineering major, who sprinted away from the building when someone pulled the fire alarm. “Just the suspense and the anticipation being all huddled up in one little room like that.”

Michael Bolanos, 19, an acting major, was in a rehearsal at a campus auditorium when he and other cast members heard about the shooting.

For the three hours that they were locked down, the actors held beer bottles — props for their show, which is set in a bar — in case they would need to defend themselves. Mr. Bolanos said the bottles were meant to “provide some twisted sense of security in that moment.”

The silence during the manhunt extended to nearby streets, where several businesses heeded shelter-in-place orders as a police helicopter hovered overhead.

At the Peanut Barrel, a bar and grill across the street from Berkey Hall, the staff locked the doors, lowered the blinds and turned the lights down after word of the attack filtered in, said Diane Barnum, the manager on duty.

A few blocks away, the staff at El Azteco Mexican restaurant also locked the doors to protect themselves and their 15 customers, said Antonio Urista, the assistant general manager. As details about the shooting trickled in, he said, the mood turned anxious and students at the restaurant began trying to reach friends who were still on campus.

April Rubin and Sam Easter contributed reporting.