BOSTON (AP) — Three major medical associations have asked Attorney General Merrick Garland to investigate and prosecute people who are threatening violence against children’s hospitals and physicians that provide gender-affirming health care.

The American Academy of Pediatrics, the American Medical Association and the Children’s Hospital Association wrote to Garland on Monday. Their demands come amid a spate of threats against doctors and institutions that provide medical care for transgender kids, sometimes including hormones or surgery for older teens.

Children’s hospitals nationwide have substantially increased security and are working with law enforcement, while some providers now need constant security, the associations said.

Garland did not immediately comment publicly, and a spokesperson did not immediately respond to an email seeking comment Tuesday. Massachusetts U.S. Attorney Rachael Rollins said this summer that the Department of Justice will ensure equal protection of transgender people under the law.

Rollins said she would not let “hate-based criminal activity” continue in her district after Boston Children’s Hospital said in August that its doctors and other staffers were being threatened with violence over its surgical program for transgender youths. The hospital is home to the first pediatric and adolescent transgender health program in the United States. Other U.S. children’s hospitals were also being harassed online.

The medical associations said in their letter that the social media threats have continued, coupled with harassing emails, phone calls and protesters at health care sites, causing “elevated and justifiable fear among families, patients and staff.” One hospital’s neonatal intensive care unit went on lockdown because of a bomb threat, they said.

“From Boston to Akron to Nashville to Seattle, children’s hospitals, academic health systems and physicians are being targeted and threatened for providing evidence-based health care,” the letter states. “These attacks have not only made it difficult and dangerous for institutions and practices to provide this care, they have also disrupted many other services to families seeking care.”

The American Medical Association and the American Academy of Pediatrics are two of the nation’s most influential physician groups, helping shape government policy at the national level and in doctors’ offices. The Children’s Hospital Association represents more than 220 hospitals serving kids nationwide.

Laws and proposed legislation in several states seeking to limit kids’ access to transgender care or criminalize doctors and parents who seek it have emboldened attacks by popular conservative Twitter accounts. Some tweets have misled their large followings about the procedures for gender-affirming care.

Boston Children’s became the focus of far-right social media accounts, news outlets and bloggers after they found informational YouTube videos published by the hospital about surgical offerings for transgender patients.

The medical associations argue that the attacks are rooted in an “intentional campaign of disinformation.” While Americans agree that online disinformation is a problem, there is widespread apprehension around federal efforts to monitor domestic, online disinformation, with privacy and free speech advocates expressing concerns about the government impinging on free speech rights.

Earlier this year, the Department of Homeland Security, for example, launched and then quickly shuttered a Disinformation Governance Board that had been intended to counter falsehoods that foreign adversaries, such as Russia, try to pump into the social media feeds of Americans.