WESTWOOD (CBSLA.com) — A professor and another man were killed in a murder-suicide inside an engineering building at UCLA Wednesday.

Gunfire was reported around 10 a.m. in Boelter Hall, which is part of the Samueli School of Engineering and Applied Science, and an alert went out to all faculty and students.

The entire campus was placed on lockdown, and the Los Angeles Police Department went on a citywide tactical alert as heavily armed officers dressed in tactical gear swarmed the campus.

Students barricaded themselves in classrooms while police investigated the possibility of an active shooter and searched for any additional shooting victims.

At around 12 p.m., police Chief Charlie Beck declared the campus safe, confirming that the shooting was a murder-suicide, with two men dead in a small office.

Police found a gun and what “could be a suicide note, but we do not know that at this point,” the chief said at least three shots were fired.

“A homicide and a suicide occurred in the engineering part of the UCLA campus on the south side,” Beck said. “It appears it is entirely contained. We believe there are no suspects outstanding, and no continuing threat to UCLA’s campus.”

The victim was identified as Prof. William S. Klug, 37, who taught mechanical and aerospace engineering.

Klug was killed by a disgruntled student, sources told KNX’s Claudia Peschiutta.

Students initially received reports of a shooting via the university’s “Bruin Alert” system. Some students reported hunkering down in restrooms or classrooms.

Many students recalled a tense two hours in which they surveyed social media for information and called loved ones for comfort.

“I told (my parents) if I die, I love you guys,” one student told KCAL9’s Kristine Lazar.

Some students posted on social media that they were unable to lock their doors and needed to improvise methods – with belts, printers or tables – to attempt to keep their doors locked.

RELATED: Students Live Tweet Barricade Tactics During UCLA Lockdown

As police later clearing classrooms, students were seen walking from buildings, often with their hands up and some being subjected to pat-downs as they left.

The large police presence created a surreal atmosphere on the campus with about 43,000 students the week before final exams.

“Seeing police walk by with assault rifles and seeing students lined up and being frisked, it was a surreal feeling,” UCLA student body president Danny Siegel said. “It was a feeling of fear, more than anything.”

Near by Fairburn and Warner elementary schools and Emerson Middle School were also placed on lockdown during the investigation, according to the Los Angeles Unified School District.

FBI, SWAT and ATF agents assisted UCLA police with the investigation.

All classes were canceled for the day, along with evening activities. Scott Waugh, UCLA vice chancellor and provost, said campus operations will return to normal Thursday, except for engineering classes, which will be canceled for the rest of the week.

UCLA officials said the university is offering counseling services to students and staff affected by the shooting.

According to UCLA, the university has designated “healing spaces” on the campus where students can gather.

Counselors will also be available for students at the Counseling and Psychological Services office.