Three D.C. fire department ambulances were improperly out of service as a severely injured police officer lay on the side of a Southeast Washington street waiting to be taken to a hospital, an internal investigation has found.

All three ambulances were stationed south of the Anacostia River and should have been available to respond to the officer, said two city officials with detailed knowledge of the inquiry, which is to be made public Thursday.

The investigation, which was conducted by Mayor Vincent C. Gray’s office, comes two weeks after a car struck the eight-year veteran as he sat on a scooter at 46th and A streets.

The investigation found that Ambulance 15 was in its station three miles from the crash. But the vehicle and its crew were not dispatched because personnel never told headquarters that they were done with their previous call. The crew was still logged in as being at Howard University Hospital in Northwest. Still, the report found, the crew should have heard the distress call and responded to the accident.

“They were out of service and off the radar,” said one of the city officials, who spoke on condition of anonymity because the investigation has not yet been made public. Had those firefighters told dispatchers they had cleared the hospital, they would have been sent to help the officer, the officials said.

The incident involving the officer, who is recovering, is the latest in a string of delays that has plagued the District’s medical services this year.

Representatives of the union for firefighters and civilian paramedics did not return calls seeking comment Tuesday evening. The head of the firefighters Local 734 has called the response time to the injured officer “unacceptable,” but blames the fire chief for policies he said are detrimental to the department. The report is sure to reignite tension between the union and Fire Chief Kenneth B. Ellerbe.

D.C. police have charged three people in connection with the collision involving the officer, which they contend was intentional. It occurred about 6:30 p.m. An advanced life-support paramedic aboard a D.C. fire engine responded first, arriving from three miles away at 6:42 p.m., eight minutes after the first 911 call.

But there was no D.C. ambulance available that night to take the officer to the hospital. A dispatcher sought help from Prince George’s County at 6:40 p.m.

The investigation concluded that 39 ambulances were available in the District that night. When the officer was struck, 30 were on other assignments. Another six were out for other legitimate reasons, the officials said.

But officials said three should have been available.

The officials said that after the crew of Ambulance 15 left Howard University Hospital at 6:26 p.m., they drove to a fire station to drop off the firefighter/paramedic. The crew then went back to their station in Southeast, but they did not notify dispatch that they were available until 7:19 p.m., the officials said.

Types of first responders

The officials said that a crew from Medic 19 requested to be relieved for a 7 p.m. shift change at 6:34. But the officials said the dispatcher told them to continue monitoring the emergency channel in case any urgent calls came in.

Medic 27 was granted permission to go out of service at 6:27 p.m. because the batteries on its heart monitor had died. But the crew should have been available to respond to an emergency that did not involve a heart attack, the city officials said.