WASHINGTON — The Secret Service is urging U.S. schools to establish teams that can assess threats and prevent shootings such as the massacre at Marjory Stoneman Douglas High School in Parkland, Florida that left 17 people dead.

In a report unveiled Thursday, the Secret Service offered schools guidance on spotting suspicious behavior and figuring out when and how to intervene. The report was prepared by the National Threat Assessment Center in an effort launched after the Feb. 14 Parkland shooting.

The report recommended forming "threat teams" drawn from the ranks of teachers, coaches, guidance counselors, mental health authorities and law enforcement to manage central reporting systems within the schools. The teams would be tasked with flagging troubling conduct, from threatening social media posts to information about students' access to weapons.

"The threshold for intervention should be relatively low so that teams can identify students in distress before their behavior escalates to the point that classmates, teachers, or parents are concerned about their safety or the safety of others," the report concluded.

The 17-page document builds on agency research earlier this year focusing on suspects linked to violence in schools and other public places. It concluded that 64 percent of attackers showed symptoms of mental illness. And in 25 percent of the cases, attackers had been "hospitalized or prescribed psychiatric medications" before the assaults.

In the Parkland case, which has driven a vocal national debate on gun safety, social workers, mental health counselors, school officials and law enforcement were all warned about Nikolas Cruz's deteriorating mental state and risk of violence before he allegedly launched the attack.

Cruz, 19, is charged with 17 counts of murder; prosecutors are seeking the death penalty.

The Parkland shooting has prompted the state to enact new safety measures, including a mandate for individual schools to create threat teams similar to those urged by the Secret Service.

According to the Florida Department of Education, the teams would be permitted access to suspects' criminal histories. Florida school team leaders also would be required to report identified threats to administrators and the suspects' parents or guardians.

Lina Alathari, chief of the Secret Service's National Threat Assessment Center, said educators have been increasingly moving to create such teams since the 2012 attack at a Newtown, Conn., elementary school that left 26 dead.

Following that assault, a survey of safety plans at 227 schools found that about 70 percent had some form of threat assessment program.

"There are some schools that have nothing," Alathari said, adding that there have been no uniform standards for evaluating threats at schools. "It's up to the schools and the (school) districts to allocate resources."

Even in schools that have taken steps to establish threat teams, Secret Service Director Randolph "Tex" Alles cautioned that attackers do not fit a common profile.

"These acts of violence were committed by students who were loners and socially isolated, and those who were well-liked and popular," Alles said in the report. "Rather than focusing solely on a student’s personality traits or school performance, we can learn much more about a student’s risk for violence by working through the threat assessment process."