Nearly a third of the District's basic life support ambulances are out of service for repairs, a situation that couldn't come at a worse time, union officials said.
The shortage of transport units comes as a heat advisory has been issued and the fire department is reporting an unusually high number of calls.
The downed ambulances mean longer transport times for patients and could be the difference between life and death, said Ed Smith, head of the D.C. fire and emergency medical services labor union.
"The welfare of the public is at risk," Smith said.
As of Tuesday morning, seven of the 25 basic life support units were out of service because of mechanical problems, Smith said. He was told that most of the units were out because of the air conditioner in the patient compartment.
City rules prohibit the use of an ambulance if the air conditioner unit is broken in the patient area.
D.C. Fire and EMS spokesman Lon Walls said the downed units would be replaced by Tuesday evening.
"We will be back up to speed," Walls said.
Smith said he warned District leaders that the fleet was in disrepair during a budget oversight hearing last month.
"Now that the summer is here, it's come to fruition," Smith said.
The problem is that the city no longer has a healthy reserve of transport units to use when a front-line vehicle goes down, he said.
Walls said four of the replacement units brought in Tuesday came from the department's reserve. The three others were repaired and put back in use.
Smith said the city got into this problem when it stopped buying new units several years ago.
"Now we're playing catch-up," Smith said.
According to department's budget, the District has ordered 10 new ambulances, with plans to buy 20 more over the next two years.