The Netflix series 13 Reasons Why was nowhere on the radar screen of West Chester Area School  Superintendent James Scanlon when he learned that a number of middle and high school students were telling guidance counselors that a new TV show was upsetting them.

So Scanlon watched the controversial series, which graphically depicts the suicide of a 17-year-old and chronicles her audio messages describing why she did it.

The Chester County schools chief said he thought the series had some valuable lessons for parents about the warning signs of suicide, but he worried about its potential impact on younger students. "If you're 12, 13, 14 years old, going through adolescence yourself ... your mind has a more difficult time processing," Scanlon said. "Not every kid, but some kids."

Recently, Scanlon joined a growing number of school officials in the Philadelphia region and across the nation in sending a letter to parents warning about 13 Reasons Why, noting that some psychologists have advised caution for younger viewers, and steering them toward more information about the program.

In the short time since the series — produced by Selena Gomez and based on a popular book for adolescents published in 2007 — began streaming on Netflix, the show has drawn a mixture of praise for its realism and growing alarm that it may disturb already troubled youths and inspire copycats by romanticizing suicide. No suicides have been linked to the series.

For those working in suicide prevention, 13 Reasons Why "was raising alarm bells that the way the story line is handled in some respects could potentially be hazardous for kids who are vulnerable," said Katherine C. Cowan, spokeswoman for the National Association of School Psychologists, which sent guidelines to its members and education organizations on who should watch the show and how to help students who may be suicidal.

Cowan said the outpouring of concern over the show has been larger than anything the group has experienced since the 9/11 terror attacks. Within six hours of posting its guidelines — its first about a TV show — she said the message had been shared 15,000 times and read by about three million people.

The series, like the book, tells of how a teenager named Hannah came to commit suicide, with the audio recordings she left behind detailing her traumas, such as cyber-bullying, sexual assault, and indifferent or uncaring adults.

Netflix has defended the program as intending to provoke a dialogue about teen mental-health issues. In addition to attaching warnings to the show's most graphic scenes, it has produced a companion documentary, Beyond the Reasons, highlighting discussions among the producers, cast, and mental-health professionals.

Still, members of the school psychologists' group who serve on committees dealing with school safety and crisis response raised major red flags after watching the series. They said 13 Reasons Why ignored best practices in suicide prevention and raised concerns about a "contagion" of teen suicides.

"You don't provide a how-to manual on how to commit suicide a certain way, and this show does," Cowan said. "They wanted to make it an honest depiction, but they ended up dramatizing it and doing things like having the character … make it a revenge suicide. That's a bad thing to reinforce. There's no such thing as a successful revenge suicide."

In a letter to parents, Palm Beach County, Fla., Superintendent Robert Avossa said his district had seen an uptick in suicide threats and self-mutilation, writing that "students involved in the recent incidents have articulated associations of their at­-risk behavior" to the series.

In the Philadelphia region, several districts have issued warnings. The Burlington City schools in South Jersey sent a letter advising parents about the series, linking to the national guidance from the school psychologists' group, and giving the phone number for the National Suicide Hotline.

Jennifer Grimaldi, director of school counseling for Washington Township High School in Gloucester County, said she had spoken with her counselors about increased student chatter about the show and sent a letter to teachers urging them to be on the lookout for any issues. "I told them, 'You are the eyes and ears,' " she said.

Julia Szorka, a school psychologist in the Central Bucks School District and past president of the American Association of School Psychologists of Pennsylvania, said the district has sent emails to parents alerting them to the show and where to go for help. In her own house, it has opened discussions with her seventh- and 10th-grade children about suicide and what to do if a friend is exhibiting signs of self-harm.

"A lot of people are watching it in high school," including her daughter, Szorka said. "A lot of them are drawn to it because it's an intense and intriguing show."

Her daughter is emotionally stable, she said, but "certainly if she had any signs of anxiety and depression, I would not be letting her watch this, for sure." Even her daughter told Szorka's son, who is in middle school, "You shouldn't watch this," she said. He isn't watching.

One big concern expressed by school officials is that considering the nature of media today, with many students streaming Netflix on their laptops or their phones, many parents may have no idea that their children are watching.

"A lot of parents didn't realize it was out there," said West Chester's Scanlon, who said the feedback he had received from parents since his letter has been positive. "They went and watched it and talked to their kids about it. The purpose for us was to make parents aware of the series and that was accomplished."

He said he has seen several teen suicides in school districts where he has worked, including a few at West Chester. "It's sad."

But unlike some of the more vocal critics of 13 Reasons Why, Scanlon said he saw positive aspects. "There are certainly valuable lessons in the series, to help people identify warning signs for suicide, that if you see them, you should go get help."