New York mayor-elect Zohran Mamdani announced that Lillian Bonsignore, the former chief of the city's Emergency Medical Services, will become the next commissioner of the New York City Fire Department.

The New York Times reported that Bonsignore's appointment marks several milestones for the nation's largest fire department.

She will be the first openly gay person to lead the FDNY, only the second woman to serve as commissioner and the first former EMS chief to take the fire department's top post.

Billionaire technology entrepreneur Elon Musk, CEO of multiple companies, including Tesla and SpaceX, who has business holdings in the city, posted in response to the appointment.

"People will die because of this," he wrote on X. Musk noted that EMS experience does not automatically equate to fire experience. "Proven experience matters when lives are at stake."

Bonsignore, 56, retired in 2022 after a 31-year career. In 2019, she was named chief of emergency medical operations, becoming the first openly gay person and the first woman to hold that position, as well as the highest-ranking uniformed woman in department history.

Shortly before Mamdani's election, outgoing Mayor Eric Adams announced that Mark Guerra would be sworn in as fire commissioner.

Guerra, who had served as interim head of the department for less than a week, will hold the position until Adams leaves office on Dec. 31. When Mamdani is sworn in at midnight on Jan. 1, Guerra's appointment will end.

Adams said the brief appointment was intended to ensure continuity of operations during the holiday period, citing the need for constant readiness within public safety agencies.

The timing of the competing events surprised some observers of city government, as acting commissioners commonly lead agencies during transitions.

Guerra replaced Robert Tucker, who resigned following Mamdani's election and cited the mayor-elect's views on Israel as a factor in his decision.