UPDATE 4:25 a.m. 5/29/2014: D.C. Fire said in a statement: “Preliminarily, it appears that FEMS personnel mistakenly indicated that they were available to respond but in fact were not available.

“Fortunately, an alert OUC dispatcher followed up with the paramedic engine company that was on scene and determined that a transport unit was still needed. A decision was made to immediately transport the patient to the closest hospital using a fire truck.

“It’s important to note that assistance was rendered quickly to the patient by an FEMS paramedic who remained with the patient until care was transferred to the hospital.”

EARLIER: WASHINGTON — A 90 year-old woman had to wait nearly 45 minutes for an ambulance on Tuesday, the latest in a series of miscues regarding the D.C. Fire Department.

A fire engine crew waited on D Street Southeast for the ambulance, which was rerouted to another call before the woman fell unconscious and the crew loaded her into the fire truck and got her to the hospital.

Why the ambulance was rerouted isn’t clear.

In a statement, the fire department says “Our preliminary investigation indicates that a transport unit dispatched to the scene may have been erroneously rerouted. The error appears to have caused a significant delay which led to a patient being transported to the closest hospital by the first arriving paramedic engine company instead of an ambulance or medic unit.

“Our review of this incident is ongoing; therefore the Department cannot provide any further comment at this time.”

WTOP’s Andrew Mollenbeck contributed to this report. Follow @WTOP on Twitter and WTOP on Facebook.