As authorities in two D.C.-area counties investigate a flawed emergency response to a June drowning, new documents show the 911 center in Montgomery County had an automatically generated map that showed precisely where the call for help had come from.

Emergency dispatchers in Maryland sent firefighters to the Potomac River after a teen called to say her friend had slipped underwater while the group was swimming in a “river.” The caller went on to say her group had been in an “inlet” off the river and that they were in Virginia.

It took 36 minutes for rescuers to reach the teen, 16-year-old Fitz Thomas, who by then had been pulled to a dock by his friends and a passerby who stepped in to help. Fitz, who was preparing to enter his senior year of high school, died.

Emergency centers have long been faced with the challenge of responding to 911 cellphone callers who may not be able to provide a precise address or may be in an open space such as a park or along a highway.

In this case, the technology that produced the map — showing the caller on the bank of a wide, languid creek in Virginia that leads to the Potomac River — is intended to help call centers pinpoint the location of an emergency. The Washington Post received a copy of the map this month after repeated requests to county officials.

Three experts who have reviewed 911 calls from the case said the map, as well as the caller’s continued explanation of her location, should have led the call center to more quickly realize that a rescue was needed at the creek — quickly accessible by roads in Virginia — not in the open expanse of the Potomac River.

“An accurate map was available on the very first call,” said Heather Hunt, a nationwide 911 expert. “Their technology appears to have worked as designed. But technology is only as good as a 911 center’s procedures, policies, training and staffing levels.”

“It just blows me away that they didn’t use the information,” said John Melcher, a 911 expert in Texas. “They didn’t use the tools they had at their disposal.

“It was clear data,” added Glenn Marin, another expert who has reviewed the case. “It gave the 911 center an immense body of information to ask questions and seek clarity.”

The response to the June 4 incident was complicated from the start.

The first 911 call, placed by Angela Stefkovich, then 16, pinged from a cellphone tower to the emergency center in Montgomery County, across the river, instead of being answered by call-takers in Loudoun County, where she was standing.

It took Montgomery 16 minutes to tell counterparts in Loudoun County about the drowning, and the Montgomery center initially said no help was needed in the response. When the Loudoun call center started receiving calls, operators there also didn’t immediately process where the teens had been swimming. A Loudoun ambulance ultimately responded.

It’s not clear if recognizing where Fitz was or a faster response would have saved his life. He was underwater for several minutes before the first call.

But the confused response from both Montgomery and Loudoun counties has prompted sharp concerns from the Thomas family, and both counties have investigated the incident.

On Thursday, the Montgomery County Council’s Public Safety Committee took up the case and received a briefing from fire and police officials. The map generated during the first call was displayed, and the county’s acting 911 director, Cassandra Onley, also described in technical terms how the map was generated.

“In this particular case, we did have Phase 2 and RapidSOS data points from the caller,” Onley said.

“It seems like the call center just overrode the information available on the map,” committee member Tom Hucker (D-District 5) said after the meeting.

Earlier, during the meeting, Hucker stressed that he has long been impressed by those working in the county’s 911 center.

“I have tremendous respect, as you all know, for our 911 operators and the importance of their work and the dedication they show and the stress they’re under,” he said.

But he said the call-takers in Montgomery and Loudoun counties, who answered several calls about the incident, seemed too tied to scripted questions. Such questions are designed to ensure key details are not missed, but experts said call-takers also need freedom to divert from them when needed.

“The scripts are very important, obviously, but it seems like there was sort of a very rigid adherence to the script, which leads to a jumping to conclusion in a couple of cases, particularly in the location of the victim,” Hucker said.

Reached after the meeting, County Council President Sidney Katz (D-District 3) said he would defer to technological experts about how the 911 center’s mapping systems performed during the call but indicated he was troubled by the overall response.

“I am concerned about every part of what took place,” Katz said.

Montgomery rescue officials have seized on the first caller’s initial words — that her friends had been swimming “in the river” — to explain why they launched a rescue effort into the Potomac River. Such a mission, by its nature, was a drawn-out process. Montgomery firefighters first had to haul boats to the Maryland side of the river, which took 27 minutes from the opening call.

In their presentation to the council committee Thursday, Montgomery police and fire officials did not say that the first caller also said she and her friends were swimming in a shallow inlet in Virginia, or that she said they were at a dock in Confluence Park, visible on Google maps as within Loudoun County.

The caller’s description that her group was in a Virginia inlet was never typed into the 911 center’s ongoing response to the call.

Melcher, the expert in Texas, said that after the first caller used the word “river,” she was getting more specific about precisely where they were — an inlet in Virginia.

“911 operators are trained to take the initial information and go more granular, and that’s what the caller was trying to do: Go more granular,” Melcher said.