Moments of absolute terror were captured in a video that has come to light, showing students at Brown University taking refuge in one of the institution’s libraries, while loud bangs from gunfire could be heard on campus.

In the video, more than a dozen frightened and tearful students can be seen crouched on the floor in front of bookshelves, while at least seven loud bangs are clearly audible. The incident occurred on Saturday during a mass armed attack that resulted in two people losing their lives and eight being seriously injured.

It has not been clarified exactly what caused the specific noises heard in the video. Shortly after the last bang, however, dozens of police officers wearing SWAT gear and carrying weapons stormed into the library, ordering the students to raise their hands.

“It’s obvious that something serious is happening; we are here to help you… just listen to our instructions and we will get you out of here,” one of the officers can be heard saying in the video.

The police asked the students to quickly gather their personal belongings before being escorted out of the building for safety reasons. In the final frames, the students appear panicked as they run to grab their bags just before the recording ends.

Authorities’ investigations into the circumstances and the exact causes of the attack are ongoing.