It’s unknown if the attack was random or if she knew the suspect who killed her.

A library security guard was stabbed repeatedly and killed by a man as she sat at her post as she sat at her post in the middle of the afternoon.

The incident occurred at around 2 p.m. at the Finkelstein memorial Library in Spring Valley, New York, when the 52-year-old female security guard was sitting at her post on the third floor of the library when a man, suddenly and with no warning, started stabbing her repeatedly with a knife while the victim screamed.

“She said ‘help, help!’ and then she said ‘I can’t breathe, I can’t breathe,’” one witness told ABC News’ New York City station WABC.

Two library patrons ran to help the woman and were able to pry the attacker off of the victim and hold him down until police were able to arrive while others tried to give the security guard CPR.

“One of our co-workers screamed over the intercom ‘stop the man’ … and he just had a smirk on his face,” another witness told WABC.

Paramedics arrived quickly but it was too late. The woman was pronounced dead at the hospital.

The suspect, a 25-year-old Spring Valley resident, was taken into custody.

Friends and colleagues gathered last night for a vigil held outside the library.

“It’s just a profound loss for us, it really really is,” said the victim’s friend Christine Ball.

“This is a place where people bring their children and family and they sit and they enjoy the library. This is a place where it should not be where we are going to need additional security just to protect us,” said Oney Barron, another friend of the deceased security guard.

The biggest question that remains is whether the victim knew the attacker or whether it was a random attack. Police are currently investigating the circumstances around the attack.

State Senator David Carlucci issued a statement in the aftermath of the attack.

“I am praying for the victim’s family in their time of grief,” Carlucci said. “Many in our community visit the Finkelstein Memorial Library, and it’s a place I have taken my own children and have always felt safe. I am extremely upset over this act of violence that incited more fear and chaos in our close-knit community.”

The suspect has not yet been charged and the investigation is ongoing.