(CNN) — A man armed with a pistol opened fire on the final day of classes at the University of North Carolina at Charlotte, killing two people and leaving four others wounded — three of them critically, authorities said.

Gunshots erupted just before 6 p.m. Tuesday as students waited for rapper Waka Flocka Flame’s concert and others prepared for exams later in the week.

“Run, Hide, Fight,” the university tweeted after it received calls on the shooting at the Kennedy building. “Secure yourself immediately!”

When officers arrived at the scene, they found several victims with gunshot wounds, as evidenced by the 911 dispatcher traffic.

“We have multiple victims in here. We’re going to need multiple ambulances,” one responding officer reported.

Said another, “We got one we need medic to really step it up on.”

Police identified the suspect as Trystan Terrell, 22. He was taken into custody without incident. As police led him away in handcuffs, he tilted his head back and smiled at the cameras.

Terrell is facing two counts of murder, four counts of attempted murder, four counts of assault with a deadly weapon with intent to kill and one count each of possession of firearm on educational property and discharging a firearm on educational property, the Charlotte-Mecklenburg Police Department said.

He is being held without bail and is scheduled to make his first court appearance at 1 p.m. Thursday.

Campus was on lockdown for hours

The university said Riley Howell, 21, of Waynesville, North Carolina, and Ellis Parlier, 19, of Midland, North Carolina, were killed. It identified the injured victims as Rami Al-Ramadhan, 20, of Saihat, Saudi Arabia; Sean DeHart, 20, of Apex, North Carolina; Emily Houpt, 23, of Charlotte; and Drew Pescaro, 19, of Apex. The campus newspaper reported that Pescaro is one of its sportswriters.

The school of about 30,000 students remained on lockdown for hours as a familiar scene replayed at the latest shooting in the United States.

While authorities worked to clear buildings, panicked students crouched in halls as helicopters buzzed overhead. Officers escorted students out of buildings with their hands up.

University officials sent an alert asking students to follow instructions from officers and warning others to stay away from campus until they received an all-clear.

“If you have not contacted your family, please do so,” the campus tweeted.

By midmorning Wednesday, the university was quiet. Reporters outnumbered students and faculty making their ways across campus. Workers were fixing a door at the library where several students sought cover during the shooting. Local and state police guarded the Kennedy building, which houses administrative offices and some classrooms, in what is typically a busy part of campus.

Exams, set to begin Thursday, were canceled through the end of the week.

He started shooting during presentations

Tristan Field said the gunfire started while he was in class.

“He just started shooting during our final presentations and we all ran out,” Field tweeted. “We were just doing presentations and someone started shooting up the room. … Why here? Why today? Why UNC Charlotte? Why my classroom? What did we do?”

Monifa Drayton, an assistant vice president at Atrium Health, told CNN affiliate WBTV that she was walking into the building to teach a class when gunfire rang out. Terrified students dashed outside the building. She helped lead them to a nearby parking deck.

“The children were absolutely petrified,” Drayton said. “And I also sat and waited with a gentleman whose girlfriend … was in the library. And at that point the library doors had been shot out and she was in there barricaded.”

The shooting happened days after a gunman opened fire at a synagogue near San Diego, killing a woman and wounding three others.

“I can’t tell you the sadness of the entire community to know that a situation like this has occurred on our campus,” UNC Charlotte police Chief Jeff Baker said. “We are all pretty much devastated.”

University Chancellor Philip Dubois called it “the saddest day” in UNC Charlotte’s history.

Officers were nearby when gunfire started

When the initial reports of a shooting came in at 5:42 p.m., officers were nearby, getting their assignments and a briefing for the Waka Flocka Flame concert. The rapper later said he was safe and nowhere near campus.

An officer quickly went to the room from where the suspect opened fire, disarmed him and took him into custody, Baker said. At the time of his arrest, the suspect was armed with a pistol, he said.

The suspect did not say a word while he was being handcuffed.

“Right now, he is not somebody (who) was on our radar,” Baker said.

Giffords: ‘You deserve better’

Frustrated officials decried yet another shooting at a campus in the United States.

“A student should not have to fear for his or her life when they are on our campuses,” Gov. Roy Cooper told reporters. “Parents should not have to worry about their students when they send them off to school. And I know that this violence has to stop.”

The governor ordered all flags in the state lowered to half-staff through sunset Friday.

Former US Rep. Gabby Giffords, who survived gun violence, sent condolences to the victims’ families.

“I am so sorry for these young people and their families. We fail as a nation when we fail to protect our children. You deserve better,” she said on Twitter.

Suspect’s neighbor speaks

At the apartment complex where the suspect lived, residents watched as police entered a unit believed to be his and stayed for hours.

“It’s alarming. It’s kind of scary. It’s surreal. You know, you hear about these types of things that happen, unfortunately, all around the country,” neighbor Harold Lloyd told CNN affiliate WCCB. “You never would think that it would occur, well that the person apparently who did it lives in the same building as you.”