The New York City Council said one of its employees was detained on Monday by federal immigration officials during a routine immigration appointment in Nassau County.

The worker, who has not been identified, is said to be a data analyst of Venezuelan descent who had no prior arrests and is authorized to remain in the country until October, Council Speaker Julie Menin said.

“We are doing everything we can to secure the immediate release of our @NYCCouncil employee… This action is a clear overreach, and we will fight for full transparency and accountability as we protect New Yorkers,” Menin wrote, in part, on social media.  

Mayor Zohran Mamdani also addressed the incident, writing, in part, “This is an assault on our democracy, on our city, and our values. I am calling for his immediate release and will continue to monitor the situation.”

CBS News New York reached out to the Department of Homeland Security for comment, but has not yet heard back.  

The City Council said the employee was transferred to a detention center at 201 Varick St. in Lower Manhattan, adding members are working to try and get him released.

“If someone has an appointment and is legally here and under work authorization, [which is] exactly what our colleague is, and then they show up to their appointment and they get taken anyway, you cannot expect people to show up for their appointments and that means people will be further in trouble,” Councilman Harvey Epstein said. “this chaos the federal government is creating is a chaos that is hurting everyday New Yorkers.”

The Association of Legislative Employees, which also called for the employee’s immediate release, said a rally will be held outside the building on Varick Street at noon on Tuesday.

Please stay with CBS News New York for more on this developing story.