Leaders from Denver’s city government, school district and court system have a message for U.S. Immigration and Customs Enforcement: back off our schools and courthouses.

In a letter Thursday to the acting chief of the local ICE field office, officials including Mayor Michael Hancock and Denver Public Schools Superintendent Tom Boasberg asked that the agency follow its own policy in respecting such “sensitive locations” while carrying out their duties.

The letter in part was triggered by a March 14 incident that rattled one Denver school community.

That morning, federal immigration agents dressed in black arrived at a residence directly adjacent to Colorado High School Charter in west Denver, a neighborhood that is home to many immigrant families, according to the letter. The enforcement action, which was planned, came during morning drop-off in plain view of students and families, it said.

“We believe this enforcement action, particularly because it was scheduled  to occur during the morning drop-off period, may have violated both the letter and the spirit of your sensitive location policy,” the letter reads. “The hour and location of this action potentially put children, staff and parents in danger should your agents have encountered resistance, and clearly caused alarm to the principal and the community served by the school.”

The 2011 “sensitive location” policy discourages ICE agents from arresting, interviewing, searching or surveilling targets of investigations while they are in schools, places of worship, hospitals or at public demonstrations like marches and rallies. Exceptions are allowed if “exigent circumstances exist,” or other law enforcement actions have led officers to a sensitive location.

A memo laying out the policy also says ICE officers or agents should consult with supervisors if a planned enforcement operation “could reasonably be viewed as being at or near a sensitive location.”

Another aspect of the March 14 incident bothered authors of the letter to ICE. According to the letter, video taken during the incident shows ICE  agents wearing black uniforms with “POLICE” in large white letters and “ICE” in much smaller type. This, the letter said, can lead people to mistakenly think that local police are involved in immigration enforcement.

A Denver-based ICE spokeswoman did not immediately respond to requests for comment Thursday.

Denver Public Schools has taken several steps to reassure immigrant families in the wake of President Trump’s election and his following through on campaign promises to adopt hard-line immigration policies.

The school board in February approved a resolution saying DPS will do everything “in its lawful power” in response to immigration enforcement to protect students’ confidential information and not disrupt learning. That includes continuing its policy of not collecting any information on students’ immigration status and involving DPS’s general counsel in any enforcement requests.

Alex Renteria, a DPS spokeswoman, said the principal of Colorado High School Charter contacted the City Council, not the school district. She said the district’s legal department could not recall other examples of ICE detentions near schools.

The principal of Colorado High School Charter, Clark Callaham, did not immediately respond to a request for comment. The school is an alternative high school serving at-risk students. As of last fall, it had 350 students, 62 percent of whom are Hispanic, DPS data show. Many are from outside the district’s boundaries.

Boasberg said in a statement Thursday that the district is required by law “to ensure that our schools are safe spaces where a student’s race, ethnicity, religion and immigration status do not create any barriers to that child’s education.”

“We urge ICE to continue to respect our schools as sensitive locations so that our students know they are safe,” Boasberg said. “When they are confident in their safety, they will be more successful as students and their success as students is so vital to our shared success as a community.”