(CNN) - A 14-year-old boy was being held on suspicion of murder Wednesday after the body of a female teacher was found in woods near the high school in Danvers, Massachusetts.
All seven schools in the suburban Boston town were closed as a result of the investigation.
The report of Colleen Ritzer's death comes two days after a student with a gun killed a teacher in Sparks, Nevada.
Authorities found Ritzer's body behind Danvers High School after the 24-year-old failed to return home after classes Tuesday, the Essex County District Attorney's Office said. Searchers found blood in a second-floor bathroom, District Attorney Jonathan Blodgett told reporters at a news conference.
He did not release the cause of her death.
The boy, who also had been reported missing Tuesday afternoon, was arrested early Wednesday after being found walking down a street, Blodgett said. There are no other suspects, he said.
He was arraigned Wednesday afternoon in Salem, Massachusetts, on a murder charge and was ordered held without bail.
Blodgett did not say whether the boy is a student at the school and said he could not release the boy's name or his connection to Ritzer because he is a juvenile.
"This is a terrible tragedy for Colleen Ritzer and the entire Danvers community," Blodgett said.
Ritzer graduated from Assumption College in 2011, the school said on Twitter. She in was pursuing a master's degree in school counseling at Salem State University, that school said in a prepared statement.
As a dedicated teacher, Colleen wanted to work with and help children with special needs," an e-mail from the university read. "She believed children have much to offer and often do not realize how special they are as individuals. In her application to Salem State she said she was dedicated to 'helping students in times of need.' "
Ritzer's aunt, Shirley Martellucci, said the family was in shock.
"We're holding up as best we can," she said.
Ritzer, who lived with her parents, was in her second year teaching at the school and was working on her master's degree, Martellucci said. She had never had any trouble with students, she said.
"She always wanted to be a teacher, all her life," Martellucci said. "It's just unbelievable that someone would take her life at such a young age."
Ritzer's students were similarly dismayed.
Freshman Spencer Wade described Ritzer as "one of the best math teachers I've ever had."
"There's not words to describe her," he said. "She's such an excellent teacher."
Other students took to Twitter to express their feelings.
Ritzer "was literally the sweetest, most harmless person ever," Twitter user samanthawxo posted Wednesday. "She always wanted to help anyone in any way she could."
"I honestly don't think I will ever look at the high school the same knowing my favorite teacher died there," Twitter user ingrahamsays posted.
It wasn't immediately clear why the district closed all of its schools after the discovery of Ritzer's body.
Danvers, a town of about 26,000 people about 20 miles northeast of Boston, has a high school, a middle school and five elementary schools.