Colleen Ritzer was known for her infectious smile, bubbly personality and admitted overenthusiasm for the subjects she taught.
Sometime on their last day at the school together Tuesday, prosecutors say that the 24-year-old math teacher and student Philip Chism crossed paths - and he killed her.
Hundreds of people attended a candlelight vigil Wednesday night at Massachusetts' Danvers High School. Many wore pink sweatshirts, bows or T-shirts in tribute to Ritzer and her favorite color.
The loss is being felt by the entire community.
"She was such a nice person, and I just feel so bad for her," said student Taryn Wendell.
Ritzer was respected by so many, and friends and family are now begging for answers.
"Something like this doesn't happen to someone like Colleen, someone who's so good and so pure, you know, it's not fair," said Jennifer Berger, Ritzer's best friend.
Ritzer lived at home with her 20-year-old brother and her sister, a high school senior.
Her family said they are mourning the death of their "amazing, beautiful daughter and sister."
Chism was new to the school, and classmates say he seemed like a nice and normal kid. He stayed silent during his arraignment Wednesday on a charge of murder.
The prosecution indicates it wants Chism to be tried as an adult, but that decision is ultimately up to a grand jury.
Court papers show the teacher and student did know each other and investigators say they have a lot of evidence, including surveillance footage showing Chism at the crime scene.
Ritzer had a Twitter account where she gave homework assignments, encouraged students and described herself as a "math teacher often too excited about the topics I'm teaching." She was a 2011 magna cum laude graduate of Assumption College in Worcester, a school spokeswoman said.
Ritzer is the second teacher allegedly killed by a student in the U.S. this week. A Sparks, Nev., middle school teacher was allegedly shot by a 12-year-old student on Monday.
The Associated Press contributed to this report.