Before she was allegedly killed by her roommate, Alexa Cannon wrote on Instagram she hoped they wouldn't "kill each other" when they became roommates

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Friends and family are paying tribute to the slain Virginia college student who prophetically posted on social media about the roommate who allegedly stabbed her to death months before her death, writing “Pray that we don’t kill each other this year.”

Hundreds packed the Second Presbyterian Church in Roanoke, Virginia, at a memorial service Sunday night for Alexa Cannon, 20, who was allegedly stabbed more than 30 times by a woman described as her best friend, Luisa Ines Cutting, 21, her roommate at Radford University.

“Alexa was a bright and beautiful person,” Rachel Thompson told local station WDBJ. The psychology major, she said, “was unstoppable. She had health setbacks but she did not let those set her back.”

“We know that her light is shining even more brightly now,” said another mourner at the vigil, WSET reports.

Last Thursday morning at about 7:45 a.m., police were called to the off-campus apartment Cannon shared with Cutting in Radford, say police.

During the harrowing call, a dispatch officer heard a woman yelling and “making reference to a knife,” according to a search warrant obtained by PEOPLE.

When officers arrived, they were met by a woman, later identified as Cutting, who was “covered in blood,” the search warrant says.

“The female turned around, placed her hands behind her back and stated, ‘Arrest me,'” it says.

When one of the officers asked the woman what happened, she allegedly responded: “I killed her.”

Cannon was stabbed multiple times, according to Jenni Wilder, a public information officer with the city of Radford.

Cutting, from Jeffersonton, was arrested Thursday and charged with second-degree murder.

She is being held on no bail in the New River Valley Regional Jail.

Her attorney, Blair Howard, said it was too early to comment on the case because her family has just hired him and he has not yet had the chance to speak with her, he tells PEOPLE.

“We understand she is undergoing some kind of medical treatment and we are trying to locate her now,” he says.

A date for her pretrial has not yet been set, a Radford General District Court Clerk tells PEOPLE.

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Social media posts indicate that the two young women were very close. But last March, Cannon wrote a cryptic message on Instagram, which has left her friends and family with many questions.

“I met this girl two years ago online and somehow we ended up living across from each other for a year,” Cannon wrote. “This summer she was equivalent to my mom in Cancun. And unimaginably she still puts up with me and now we’re living together next year. Love you more Lu and everyone pray that we don’t kill each other this year.”

Police have not yet revealed a motive in the attack.

“I’m lost for words, to be honest,” Shelton Lewis, a junior who lives near the apartment the two best friends shared, told WSET.

“I really want to know what was the motive behind it because they were best friends since Freshmen year, and that was in 2016. Now it’s 2019 and this has happened,” he said.

• with reporting by CHRISTINE PELISEK