Police: Man kills woman with 10-inch hunting knife in 'unprovoked' attack at Massachusetts library

A 22-year-old woman was fatally stabbed and an elderly man was injured in an "unprovoked" attack at a Massachusetts public library Saturday.

According to CBS Boston, 22-year-old Deane Kenny Stryker was sitting in the reading room at the Winchester Public Library when a man approached from behind with a 10-inch hunting knife.

Other library patrons reportedly watched in horror as the man stabbed the woman multiple times in the head, chest and torso. A 77-year-old man was among those attempting to help the woman as she ran toward the door. He was stabbed in the arm before other patrons could subdue the attacker.

Both victims were transported to hospitals. The woman died from her injuries.

The suspect was identified as 23-year-old Jeffrey Yao of Winchester, Massachusetts. He was arrested and charged with one count of armed assault with intent to murder and one count of murder, according to police.

In a news conference Saturday, Middlesex District Attorney Marian Ryan said Yao "was known to police."

According to the Boston Herald, neighbors of Yao had warned authorities about him in the past. They said the 23-year-old's behavior had become increasingly erratic in recent months.

One neighbor spoke of an incident in which Yao allegedly tried to smash their door down at 3 a.m. late last year. The neighbor said he warned authorities that Yao "will kill somebody."

Other neighbors said Yao had started keying cars, slashing tires and smashing bottles in the street. A mother said she would keep her kids inside the house whenever Yao was around. "People started buying bats to have by their beds," she said.

Yao is set to be arraigned Monday in Woburn District Court on charges of murder and attempted murder.

The victim was reportedly an aspiring doctor who was well known in the community.

“Deane is a special kid and overcame some real obstacles in her life. She decided early on that she wanted to be a doctor,” a family friend said.

Stryker had been in her first year of the medical program at the University of New England. The university's president, James Herbert, released a statement following her death:

The Winchester Public Library will remain closed until at least Tuesday while police conduct an investigation.