A deadly shooting has shaken the student body on Northern Arizona University’s campus in Flagstaff.

According to police, a student produced a handgun during a late-night altercation near an all-Greek dormitory and shot four others — one of them fatally. The suspected gunman, an 18-year-old freshman, is now in custody.

Students across campus were shocked by the violence, which occurred around 1:20 a.m. Friday.

But at a predawn news conference, school officials said the campus was secure and that students were expected in class on Friday.

“We are sensitive to the tragedy and we are asking the faculty to be sensitive to the needs of our students and their families,” school president Rita Cheng said.

But, she added: “This is not going to be a normal day at NAU. Our hearts are heavy.”

On social media, students expressed disbelief. One of their own had been killed and three others were hospitalized — but classes, tests and lectures would continue, like it was any other day.

Some students complained that they had been awake all night, waiting for the latest news about the incident and fielding calls, texts and messages from worried loved ones in other parts of the country.

“So many of us have been up since 1, 2, 3 in the morning,” one student wrote on the anonymous social media app Yik Yak, “how do they expect us to function?!”

“Especially knowing one of us is dead and three others are wounded?!” the person continued.

Others noted that the school’s decision seemed disrespectful to the victims of the shooting.

“We’ve lost one of our own,” noted another Yik Yak user.

“No time to grieve kids!” wrote another user, sarcastically. “Quick Quick get to class nothing happened here move along school will proceed as normal!”

Others advocated against attending class in protest.

“Do not go to class [if] you feel you are not emotionally stable enough to,” counseled one Yik Yak user. “Take care of yourself.”

But some students criticized their fellow classmates for being more concerned about whether they would need to attend class on Friday than they were about the well-being of the victims.

“Don’t use this tragedy as a ploy to get out of class today, this tragedy will be with us every day now,” another user noted.