High school students discovered their teacher's body inside a Placentia, California, classroom Monday after the 31-year-old woman hanged herself. Pictured, a teacher stands in an empty classroom. Reuters

High school students in Placentia, California, discovered their dead teacher's body inside a classroom Monday after the 31-year-old woman apparently hanged herself. The students found the El Dorado High School teacher hanging in her classroom around 8:40 a.m., police said.

"When police and fire arrived, the teacher was in cardiac arrest," Placentia police Lt. Eric Pointe said. "After several minutes, she was declared deceased at the scene." Investigators suspect the teacher hanged herself in the classroom, Pointe said. She not immediately identified pending family notification. The Los Angeles Times, however, said she had been identified by students on social media as photography teacher Jillian Jacobson.

The death shook the high school campus, with students leaving the school in tears. Leo Amaya, 16, of Placentia said he was in the teacher's class his freshman year. The woman was upbeat and loved to teach her photography class outdoors, the student said, according to local media reports. "If you take into account how everyone reacted by crying and being upset, you'll see how everyone was completely surprised that it was her," he said. "She gave no signs of being depressed or sad."

Grief counselors were on hand for students and teachers. School was expected to resume under a normal schedule Tuesday.

Some students took to Twitter Monday to honor their teacher. “RIP Mrs jacobson. Hard to say goodbye to a great friend, family, and staff member…” Liz Madrigal tweeted. Another person wrote that she “really brightened up everyone’s day.”

Placentia is in northern Orange County, near Los Angeles.

Teacher suicides have made headlines in recent months across the nation. Last year, a Texas high school teacher took his own life a day after he resigned over allegations of a sexual relationship with a student. In Connecticut, a middle school teacher jumped off an Interstate 95 overpass in an apparent suicide in October.

Suicide was a leading cause of death for all ages in 2010, according to the Centers for Disease Control and Prevention. Women are more likely than men to have had suicidal thoughts. There were 38,364 suicides in 2010 in the United States, or roughly 105 each day.