weird roommate

I barely know this roommate, I know her name and degree. Thats literally it. I try to make small talk to get to know her better but she gives very short answers and she doesn't want to talk. Whether she has social anxiety or generally doesn't want to talk is fine, it doesn't matter to me.
But the other day, it was like 7pm and she just started screaming, crying and smashing stuff in her room and it was terrifying to hear. I had to call security and when they came, she didnt calm down and she threw food at them and still screamed. She sounded psychotic. It lasted for about an hour and it kept escalating to the point where the police had to be called. She got taken in to the station for the night and I saw her yesterday back in our flat and she apologized for the way she behaved. I'm glad she did because you knew it was wrong but I never saw someone act like that ever. It was the type of behavior you only see in films.
She smashed a bottle in her room, a bottle in the kitchen. Threatened security and the police. The police found a drawer full of painkillers. Police said she was also drunk so that could be the cause of it though I doubt it. I've been many drunk people in my life so it has to be smt more. A part of me does think its mental illness especially because of the pills. My flat mates think its a mix of alcohol, drugs and mental illness.
Even though she apologized, I still feel very on edge about it. I know it sound stupid but whenever I'm alone in the kitchen, I just get a vision of her behaving like that again and I get caught in the cross fire.
This was the first time she acted like this. Again I barely know her - we barely see eachother and idk seeing as I'm pretty much in the flat 24/7. But yeah what do you think caused it?