INDIANAPOLIS (AP) — Indianapolis plans to replace its entire fleet with electric and plug-in hybrid vehicles by 2025 — the first major U.S. city to take such a step.

City spokesman Marc Lotter said Mayor Greg Ballard will announce the move Tuesday.

Lotter says Ballard will sign an executive order mandating the city replace its current sedans with electric or plug-in hybrids and phase in fire trucks and other heavy vehicles that run on compressed natural gas.

New vehicles would be purchased as older vehicles are retired.

Lotter says city officials also will ask automakers to develop a plug-in hybrid police car, as this doesn’t yet exist.

He says research by city officials and the U.S. Conference of Mayors found no other major U.S. city has announced it will convert its entire fleet.