The collision occurred about 8:22 a.m. in the 13200 block of West Jefferson Boulevard as the ambulance was responding to an emergency call with its lights and sirens activated, the LAFD said in a statement.
The firefighter-paramedics gave the woman medical assistance but were unable to revive her, the statement said. She was pronounced dead at the scene.
Her identity was not immediately released.
The man who was driving the taxi and two LAFD firefighters were transported to a hospital "due to the mechanism of the collision" but were not seriously injured, the news release said.