DENVER » As the horror unfolded for police first on the scene of the Colorado theater massacre, the officers repeatedly sent out urgent pleas for more ambulances even as a two-man crew and their rig were idling just a few miles away.

Radio traffic from last Friday’s shooting in Aurora, Colo., showed emergency personnel struggling to grasp both the scope of the tragedy and mobilize a response.

While some ambulances were quickly called to duty, it took dispatchers more than 20 minutes into the crisis to ask the Cunningham Fire Protection District and other nearby agencies to provide aid at the multiplex in suburban Denver.

By the time the Cunningham crew arrived, it was more than a half hour after authorities got first word that a gunman opened fire at a packed midnight showing of the new Batman film "The Dark Knight Rises," killing 12 people and injuring dozens of others.

The ambulance delays came during crucial minutes for the injured victims, though it’s not clear whether a faster response would have saved more lives.

Officials have declined so far to release call records of the response, and the Aurora Fire Department declined to discuss the handling of ambulances from that night.

Experienced emergency responders say no response will ever be perfect. Residents in the Denver area are well aware of the turmoil that comes with mass tragedies, as police were criticized in 1999 for waiting outside Columbine High School instead of immediately pursuing two gunmen who went on a killing rampage inside.

"You always find things that you can improve the next time," said Robert Finn, a retired police and fire chief from the Dallas area who added that officials will usually conduct a post-incident analysis after big tragedies.

On the police radio transmissions, officers said they lacked sufficient medical support for about 30 minutes after the 911 calls came flooding in around 12:39 a.m. and that medical teams didn’t report getting inside the theater for about 24 minutes. It wasn’t clear whether police efforts to secure the multiplex contributed to the delay in getting medical teams inside.

Dispatchers began their response by quickly sending one ambulance to the scene, followed by another about three and a half minutes into the response. A third ambulance soon followed.

Over the next several minutes, first responders reported on the extent of the casualties, calling in the numbers of wounded in their areas: One said three were shot in one location. Another said someone was shot twice in the back. A third asked that rescue personnel go into the theater to help "multiple victims."

About nine minutes in, one officer in an urgent voice declared bluntly: "I need as many ambulances as we can." Four had been dispatched at that time, according to one person on the scanner traffic.

An officer said he was going to take a victim in his car.

Eleven minutes in, a first responder again barks: "Dispatch, get me some ambulances!" A coordinator replied that Rural/Metro — the private ambulance provider for the area that also declined comment on the response — was sending all available units in Aurora.

The Cunningham unit, however, had not been called and sat idle for 10 more minutes. The department operates separately from Aurora officials but coordinates with them on a near-daily basis.

District Fire Chief Jerry Rhodes said one of his units on duty that night had no idea about the turmoil unfolding a few miles away, in part, because they were likely sleeping due to the 24-hour-long shifts they typically staff.

Rhodes said the district’s crew, including one paramedic and one emergency medical technician, received the plea for help at 1 a.m. — about 21 minutes after officers first began rushing to the scene.

Denver Health Paramedics, which had two ambulances on the eastern side of Denver that is closest to Aurora, got its call to provide support three minutes after Cunningham. One of the units was eight minutes away.

West Metro Fire Rescue also got a similar call to send medical support — 15 minutes after the Cunningham request.

Medical teams that were first to arrive appeared to deal with the wounded as they came upon them, which meant first handling the moviegoers who made it outside. That left other severely wounded patients inside the facility.

While fire officials in Aurora declined to comment about how they responded, Deputy Chief Chris Henderson told reporters after a brief memorial service Wednesday night that the firefighters did an incredible job.

"The lives that were saved that night. That’s the comfort you take from this," Henderson said.

Scot Phelps, an experienced paramedic who works at an emergency management academy in New York, said it was clear that the lack of ambulance transport was a problem in Aurora. He said that could be due in large part to the structure of modern emergency systems, which he said are poorly funded, leaving few ambulances readily available.

Before the aid call went out to the other agencies, officers repeatedly implored dispatchers for more medical support and bemoaned the resources they had at their disposal. At one point, they also asked for an accounting of what resources were on the way.

"To be honest with you, sir, I don’t know an exact count of ambulances," one person said. They added that two more ambulances were getting dispatched then.

Over the span of 10 minutes, officials mentioned multiple times the situation of a child who they could not evacuate from the theater and needed rescue. About 15 minutes in, one officer asked whether he had permission to take victims with his car.

"I have a whole bunch of people shot out here and no rescue," he said in a hurried tone. The response came immediately: "Yes, load them up, get them in cars and get them out of here."

At 18 and 20 minutes in, police coordinators repeated their calls for more medical assistance. At 27 minutes, an officer was still reporting that they were loading patients into the back of patrol cars. "Any ambos we could get would be nice," he said.

Thirty minutes into the chaos, an on-scene commander made a final, exasperated plea. He asked about Cunningham’s resources and whether another private company in the area — AMR.

"Anybody else that’s in the area that we can contact?" he asked. "Maybe Cunningham? Somebody that we can get a hold of? AMR? Anybody?"

The response came back from a woman’s voice that sounding equally worn. "We’re working on finding additional transport rigs to assist us with transporting from the scene," she said.