Michigan State University student Dominik Molotky was in class on Monday evening when he heard a gunshot in the hallway, just outside the door.

"I was sitting next to the nearest door and thank god that my fight-or-flight response kicked in because, right when that first gunshot went off, I booked it to the far corner of the class," Molotky, a senior, told ABC News in an interview Tuesday on "Good Morning America."

A couple seconds later, the gunman entered the classroom and fired "three to four more rounds," Molotky said.

"I was ducking and covering," he recalled. "I think one of the students in my class got hit."

When the gunfire stopped for "30 seconds to a minute," Molotky said, he and his classmates started breaking open a window so they could escape.

"There was glass everywhere," he added. "We broke open the window and climbed out of there, and I booked it back to my apartment."

Molotky and other students recounted their horrifying experiences as the mass shooting unfolded at multiple locations on MSU's main campus in East Lansing, Michigan.

ABC News spoke to Matt Riddle, who said his daughter Emma survived the bloodshed at Michigan State University on Monday night, 14 months after surviving another deadly mass shooting at a high school in Oxford, Michigan.

The shooting at Oxford High School on Nov. 30, 2021, left four people dead and seven others wounded.

"Having been through it in Oxford, it helped her understand what she needs to do in these situations," Riddle told ABC News during an interview on Tuesday night. "I don't like that she has those tools. I wish she didn't, but she does."

Classes at Michigan State University, which were canceled this week in the wake of Monday night's deadly mass shooting, will resume on Feb. 20, school officials said Tuesday.

Meanwhile, an on-campus vigil in honor of the victims, all of whom were students, is scheduled for Wednesday night.

"We are devastated by this tragedy and wrap our collective arms around the victims' families and friends who face unimaginable injury and loss," MSU's vice president of university advancement, Kim Tobin, said in a statement announcing the details.

Arielle Anderson, a junior from Grosse Pointe, Michigan, was one of the three Michigan State students killed in the shooting. Her family remembered her as a "precious daughter, granddaughter, sister, niece, cousin, and friend" in a statement shared Tuesday evening through her mother's employer, Comerica Bank.

"As much as we loved her, she loved us and others even more," the family said. "She was passionate about helping her friends and family, assisting children and serving people."

Anderson, who was described as "sweet and loving with an infectious smile," wanted to be a surgeon, her family said.

"Driven by her aspiration to tend to the health and welfare of others as a surgeon, she was working diligently to graduate from Michigan State University early to achieve her goals as quickly as possible," the family said.

"We are absolutely devastated by this heinous act of violence upon her and many other innocent victims," the statement added.

Hundreds of people gathered at memorials, prayer services and candlelight vigils across Michigan on Tuesday night to honor the three students who were killed and five others who were injured in Monday's mass shooting at Michigan State University.

More vigils are planned for the rest of the week, including one scheduled for Wednesday at 6 p.m. ET at The Rock, a 149-year-old landmark on MSU's main campus in East Lansing.