UNLV senior recounts barricading in classroom, saying goodbye to his dad during mass shooting

University of Nevada, Las Vegas senior Mike Henderson had just left his classroom in Beam Hall and was in a hallway when he heard about eight gunshots on Wednesday.

"An alert came to my phone from UNLV [saying], 'Shots fired -- run, hide, fight,'" Henderson said, and that's when he knew "it was real."

"I immediately went into a neighboring classroom on the second floor and we began the shelter in place. Lights went off, everybody got quiet. Everyone was nervous," he said.

The students and professor barricaded the door with desks and tried to stay quiet, he said.

"We wanted to make sure if the shooter was coming down the hall, he didn't think anybody was in the class," he said.

Henderson said he called his dad. He said other students, panicked and crying, also called their parents.

"If you're not gonna make it out of a situation, you want to talk to your loved ones," he said.

"I said, 'Dad, I have to go, if this is the last time we talk, I love you,'" Henderson recalled. "I lost my mom a few years ago, so my dad is like my lifeline. Just saying goodbye to him was tough."

Three faculty members were killed and one faculty member was injured in the Wednesday mass shooting at UNLV. Two of the victims' have been identified as 64-year-old Cha Jan Chang, a professor, and 39-year-old Patricia Navarro Velez, an assistant professor, the Clark County coroner said.

The victims were killed on different floors of the business school building, law enforcement in Las Vegas told ABC News. The suspect's movements through the building would suggest he may have been targeting his victims as he carried out his rampage, law enforcement said.

The first officer was on scene 1 minute and 18 seconds after receiving the call, according to UNLV police.

After the shootings, it appears the suspect encountered two UNLV police detectives outside the business building, near the student union. The suspect died at the scene following a gunfight with police.

Henderson said, after about 25 minutes barricaded in the classroom, police arrived at their door and escorted them out of the building.

As they were led out, Henderson said he heard more shots coming from the student union next door. Once outside, Henderson said he saw a bloody body, face-down on the ground.

First-year UNLV student Brayden McDermott, who was also on the second floor of Beam Hall, said he first heard an alarm go off.

"We were confused what was going on because a lot of us were first-years, we didn't know that this is what it sounded like, this is what this was," said McDermott. "Then all of us just heard somebody scream ... there's a gun."

"And everybody starts running in the opposite direction," said McDermott. "I nearly got trampled, like some girl fell over herself going down the stairs. And I, we don't know everything that happens. It's awful."

McDermott clarified he did not hear any gunshots but sprinted out of the building once he heard someone say there was a gun.

"I'm panicking. My lungs are burning," said McDermott. "I was terrified."

McDermott said he and hundreds of other students waited for nearly eight hours at the Thomas and Mack Center during the aftermath of the shooting, until the dorms opened up again.

He also said he wasn't surprised by the shooting given the frequency of mass shootings in the U.S.

"I don't mean this to sound callous or harsh but like, this has happened so much. People don't care anymore and that is a shame," said McDermott.

"No one is untouchable," said McDermott. "And if anywhere was untouchable, we'd all be living there."