Students and staff at Simon Fraser University's main campus in Burnaby were startled to see armed Mounties flooding the area near the library and a helicopter circling overhead Tuesday afternoon.

So, naturally, they looked to the university's official communications channels for some kind of update on what was happening.

"I was checking my Twitter nonstop and nothing was coming from them," said Adrienne Blas. "It would have been great to see some kind of information so that I would have known what was happening."

Blas watched the massive police presence build while babysitting a young child at a nearby playground. She said the experience was especially worrying because she was responsible for the safety of another person.

She wasn't the only person left wondering what was going on and frustrated by the lack of information.

Tayla Jackson said she found out about the incident on a Facebook group that normally posts information about where parking tickets are being issued on campus.

"Immediately I go to SFU to see if there's anything on Twitter and there's nothing," Jackson said.

She started messaging friends who were closer to the scene, who sent back photos and videos of helicopters and heavily armed police officers.

When word finally came from the university, it was just an acknowledgment that the situation was happening and an instruction to contact RCMP for more details, Jackson said.

"A hundred per cent, they dropped the ball," she said, when asked about the university's response to the situation.

Jackson said the school should have activated a campus notification system to let people know what was happening.

"They were never going to fly under the radar with the amount of cops that were up here and the amount of firearms that were up here and helicopters," she said. "It's in the middle of campus in the middle of the day. Everyone was exposed to all of these terrifying things and there was nothing acknowledged until after the fact. And even after the fact, it was cryptic."

For the record, here's what RCMP say happened:

Mounties from eight different units, plus the Combined Forces Special Enforcement Unit converged on the campus just before 2 p.m. They were responding to calls about a man with a gun near the library.

They arrested a 19-year-old suspect in a classroom near the library. Police say he was wearing a hat with the RCMP crest on it and had a replica firearm in his bag. No charges have been laid, police said.

When CTV News Vancouver asked SFU why the campus notification system wasn't deployed in this situation, a university spokesperson declined to explain further, saying only that everyone was safe and the situation had been resolved.