One student calls her "the nicest teacher anyone could ever have."

Students at Danvers High School say they're stunned by the killing of 24-year-old math teacher Colleen Ritzer, whose body was found in the woods behind the school early today. Investigators located her body after first discovering blood in a second floor school bathroom.

Authorities have charged a 14-year-old student at the school with murder. He is described by classmates as soft spoken and pleasant. A teammate on the school's soccer team said he "wasn't violent at all."

He was ordered held without bail after his appearance today in adult court.

One 17-year-old who was a student in Ritzer's geometry class last year says she was a warm, welcoming person who would stand outside her classroom and say hello to students she didn't teach.

She always had a warm smile on her face," Chris Weimert said.

Another student said kids related to the young teacher, who liked to wear jeans and boots like the students wore.

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."

All public schools in Danvers, which is located 20 miles north of Boston, were closed today.