On a recent visit to a Bronx emergency room, Dejohn Jones witnessed something shocking: a young child who had apparently been removed from his school, who was now surrounded by police officers and strapped to a gurney.

“He was screaming, ‘Unstrap me!’” she remembered.

It’s an all-too-common sight in the Bronx, where schools in community districts 9 and 10 called emergency medical workers to remove students in crisis more often than schools in any other part of the city over the past three years, according to advocates. Those districts encompass some of the city’s poorest neighborhoods, but parents say their schools are forced to over-rely on emergency workers because they are not equipped to meet their students’ mental health needs.

Now — in the wake of a fatal stabbing in a Bronx school — a group of local parents is calling on the city to provide more support services in their schools as a way to prevent mental-health crises and violent outbursts. At a rally this week, the New Settlement Parent Action Committee demanded more social workers in District 9, along with better training for teachers and school leaders.

“It’s evident to me that schools are now deficient in these areas,” said Amanda Gonzalez, a parent leader for the committee, “and there are fewer supports for students and families like mine.”

District 9 includes Yankee Stadium and the neighborhoods of Grand Concourse, Morrisania and Tremont. It borders District 12, where police say an 18-year-old student at Urban Assembly School for Wildlife Conservation used a switchblade to stab two classmates during history class, one fatally. Though schools Chancellor Carmen Fariña recently said there weren’t clear warning signs that something was wrong, reports suggest bullying was a factor, and that the student struggled with mental health difficulties such as depression.

The needs in District 9 are immense, according to the committee.

Last year, 20 percent of students were homeless — the highest percentage in the city, according to the Institute for Children Poverty and Homelessness. Over the last three years, there were more than 280 emergency calls from District 9 schools and 230 transports to the hospital, according to Bronx Legal Services.

Meanwhile, the action committee says there is only one social worker for every 589 students in the district — nearly 12 times higher than the 1-to-50 ratio that the National Association of Social Workers recommends for high-needs communities. The District 9 parent group is calling for the education department to hire more social workers to bring the district in line with those recommendations.

Wesley Guzman, a sophomore at the Bronx Academy for Software Engineering in District 10, said his school tries to support all students, but the one social worker and two guidance counselors on staff are seriously overworked. Guzman said they are important resources for helping students deal with issues in a healthy way rather than acting out.

“I confide in these people because they bring a culture of real and meaningful safety,” he said.

Jones, a parent leader with the committee, said more mental health support will not only keep students safe, but also steer them away from trouble that could lead them into criminal justice system.

She added that students of color rarely get the full support they need. However, she said she was encouraged that officials from the education department attended the rally on Wednesday.

“There’s work that’s being done,” she said, “little by little.”

Education department spokeswoman Miranda Barbot said the District 9 superintendent has offered training in how to “de-escalate” and manage situations that could lead to behavior crises. She also pointed out that there are 21 “community schools” in the district, which provide extra social supports to families.