Mello said Sanchez had a severe neck injury, but did not describe the attack.

A 16-year-old boy was taken into custody by a school resource officer in a matter of seconds, Mello said.

The boy was later charged as a juvenile with murder, but could be charged as an adult after his arraignment in New Haven on Monday, CBS 2’s Don Champion reported. His name was not released because of juvenile offender laws.

Investigators are looking into the possibility Sanchez had just turned down her alleged attacker’s request to attend prom together.

“I guess he just got really upset by that,” a student told WCBS 880’s Paul Murnane. “That’s what I’ve heard so far.”

Others wondered if some jealousy was involved in the attack. They said Sanchez had a boyfriend who was taking her to the prom. Students said they think the suspect may have been a former boyfriend, CBS 2’s Sonia Rincon reported.

Police did not confirm anything that could shed light on motive.

“This is something that everybody wants to get to the bottom of and find out why it happened and what we can do to make sure it doesn’t happen again,” Mello said.

16-Year-Old Girl Stabbed To Death At Connecticut High School Hours Before Junior Prom

The attack was witnessed at least in part by a school staff member, Mello said.

Police called the deadly stabbing an isolated incident and later deemed the school safe. Students were sent home early.

“The unexpected and sudden loss of our beloved family member Maren Sanchez is both shocking and devastating,” her family said in a statement. “After a terrible experience like this we can never forget the lessons about school violence that must be learned from this tragedy. The unprovoked attack on Maren this morning has unfortunately for our family resulted in the permanent loss of Maren Victoria Sanchez, a bright light full of hopes and dreams with her future at her fingertips. Maren should be celebrating at her prom this evening with her friends and classmates. Instead we are mourning her death and we are trying as a community to understand this senseless loss of life. We need to ensure that more young children are protected from violent attacks at school.”

“We are obviously devastated by the loss of one of our students,” School Superintendent Elizabeth Feser said, adding that the honor student and athlete was well-liked by her peers and teachers.

“This is a difficult day for Milford. It’s an even more difficult day for the Jonathan Law High School community,” Mello said. “Anytime there is a death, it’s tragic. It’s especially difficult when it’s a young person, like we see this morning.”

Counseling services were to be provided to students at the school throughout the weekend, Champion reported.

Friday night’s junior prom was postponed. Instead, students attended a memorial tribute on a nearby Milford beach, Champion reported.

Sanchez’s boyfriend posed for a picture with her prom dress, surrounded by friends on a pier. It was the very dress Sanchez showed off on her Facebook page.

“She was just really fun loving, nice person. She was always happy and it took a lot to get her down,” friend Evelyn Castro said.

“She was like my best friend and now she’s gone,” Brittany Welkes added.

Flags in front of the school were lowered to half-staff, WCBS 880’s Peter Haskell reported.

At the other end of the building, students had already spray-painted a large rock the color purple and wrote “Mare” and a heart in white.