(CNN)The panic wasn't immediate for Pranasha Shrestha and her classmates.
But with reports of a possible shooter or shooters nearby on the UCLA campus, it wasn't long before that changed.
Especially when the dozen or so students realized that one door in the classroom could be secured, but the other couldn't.
"The first door was easy to lock, but the second door required a bit more ingenuity," Shrestha told CNN on Wednesday evening.
Some people wanted to go to find another place to hide, but with rumors going around that the shooter was in their building, Boelter Hall, staying put was the best thing to do.
"One of the students in the classroom, the most flustered one came up with the idea" of tying the door using a belt and a projector cable to a table, she said.
In some classrooms on the UCLA campus Wednesday, as students swapped texts about the shootings that ended with two men dead in a nearby building, some people confronted doors that swung out and couldn't be locked.
Students posted images of cords and belts being tied to the hinges and handles to prevent someone from getting in, prompting questions of safety and preparedness on the campus for some 43,000 students.
A top campus official said the school wants to learn from what happened Wednesday.
"Our primary goal right now is to review all of our security procedures to make sure our campus is as secure as possible. We were pleased in the way that notifications went out, (and) troubled by some reports of unlocked doors, but we want to review everything and make sure that the campus is as safe as possible," UCLA provost Scott Waugh said.
Googling how to secure a door
Even at doors that did lock, some people tied them as an extra measure.
Miguel Rodriguez and about 120 other students were in an auditorium classroom on the UCLA campus when cellphones started buzzing with news of the emergency.
Rodriguez, a 32-year-old senior majoring in Spanish, said he and others raced to close the doors to the large room.
They were stuck open, unable to be closed without an Allen wrench.
So Rodriguez and his professor "made the decision to take our chances."
They led the group 100 feet down a hallway to a file storage room where they could lock the door. For extra safety, they pushed a table in front of the door.
Daphne Ying said she was notified of the situation by a Bruin Alert, university messages that are sent to email, text and Twitter accounts. But the reported shooter was on South Campus and she was on North, so she went to class instead of returning home.
Ying and her classmates were in one of those rooms where the door opened out so once they understood the gravity of the situation they began searching on the internet for "How to lock a swinging door."
Someone suggested tying a projector cord to the door handle. Then they tied that to a chair that was bolted to the floor.
After 30 minutes, the silhouettes of four officers appeared through a wall made of opaque glass.
"They tried to open the door and until we heard them speak we were very scared," she told CNN. They never said anything to us though and didn't open the door."
Ninety minutes later the students received the all clear message.
Carrie Rapaport, a 42-year-old senior, said that initially her class was in a room where the door couldn't be locked, so the professor and the teaching assistant led them to a place more secure.
Even with the door locked, they decided to make it more secure. Rapaport donated her belt as did another student, and a man in their class bound the hinge so it wouldn't open.
"I know we felt better about doing it. It's something that actually does work," Rapaport said. "The hinge won't budge and won't allow you to come in."
'Secure the door'
The UCLA website has instructions for people on campus who are caught in an active shooter situation. It says what to do if someone is in a hallway, in an auditorium, in an open space, is confronted by a potential shooter or is in class.
"If you are in a classroom, room or office, STAY THERE, secure the door and turn off the lights. Remain silent."
If the door cannot be locked and opens in, the school says, use heavy furniture or door wedge to barricade the door.
Students said there are no drills like the ones they might go through in high school to simulate what to do if a gunman attacks.
Expert: Change locks on old doors
One expert told CNN that it is just not feasible to go through such drills with so many students and personnel.
"What we do recommend is that key faculty and staff who would be critical in activating emergency response plans do drills at least annually," Amanda Botelho Robbins, a senior security consultant for San Diego-based TSG Solutions, said.
Robbins said it is common for doors in older buildings, many built before school bloodbaths like the Columbine massacre in 1999 and Virginia Tech shootings in 2007 became a national concern, to be hard to secure from the inside.
Universities should change the locks on any door that cannot be locked from the inside, she said. That can cost $200 to $400 per door (more for a cafeteria or auditorium door), but it is worth it, she added.
"We also recommend electronic security systems, especially on exterior doors," she said, referring to giving campus police the ability to remotely lock doors into buildings.
Some universities are beginning to think about access controls for interior doors, too. But that's very expensive, she said.
Freshman Celina Avalos said first-year students are lectured about sexual assault, dangers of alcohol and mental health services.
Avalos, 19, was in her dorm when the alerts went out and she locked her door, which can be "double locked" by turning the handle in a certain manner.
"My first instinct was to stay in my dorm, don't open the door to anyone and don't go out anywhere until further notice," she said.
It took about two hours for the campus to be swept and declared safe by the authorities.
Waugh, the university provost, said he was happy with the performance of campus police and other emergency responders.
But when asked further about the unlockable doors, he repeated his call for a safer campus. "We will review the locks on the doors, and any security issue that has arisen during the course of today," he said.
CORRECTION: An earlier version of this story incorrectly identified a UCLA student who discussed how he and others sought sanctuary after they realized they were in an auditorium with doors stuck open. He is Miguel Rodriguez.