It was nearing the beginning of Mother’s Day weekend in Montgomery County when police dispatchers began hearing a strange noise over their radios.

Instead of being able to communicate with officers, they heard a sound like a “bonk.” Then another “bonk.”

Calls were not going through.

“They couldn’t explain what was happening,” said Montgomery County Fire and Rescue Service Capt. Dallas Lipp, who is involved with the management of the county’s public safety radio system and got a phone call from the supervisor on duty late on the night of Friday, May 10. As the two officials were talking, Lipp said, the radio failure happened again.

The noises were the start of a 14-hour-long outage that disrupted communications through the aging system, which is used by police, fire, the sheriff’s department and others in the county of 1 million residents just outside Washington.

It was, Lipp said, “by far the longest disruption we’ve had since we went live on the network.”

That weekend was quiet — no shootings or fights, large fires or other major emergencies — so the outage didn’t significantly disrupt public safety, officials said. Police used their in-car computers and switched to alternate radio channels to speak with dispatchers and other officers.

But the incident has become a rallying cry for some officials and advocates frustrated with what they say are unacceptable delays in upgrading the communications system, which was installed nearly two decades ago.

The $45 million project to replace the current 11-tower system with an upgraded 22-tower system has been in the works for years, and Lipp says the goal was to have the infrastructure in place by 2013. Than plan was delayed by contracting and other issues, and the project also suffered from limited resources for several years during the county’s recovery from the Great Recession.

Now critics say the timetable could be reset again following a recent decision by County Executive Marc Elrich (D) to look for new locations for two communications towers that were supposed to be placed near communities that don’t want them.

In an era of mass shootings at schools and other public places, and in a jurisdiction where a gas explosion and fire killed seven at an apartment building in Silver Spring in 2016, some officials say the county cannot afford to wait.

“It’s a matter of life and death,” said County Council member Hans Riemer (D-At Large). “This thing could go down right now — it could be down as we speak.”

Andrew Kleine, chief administrative officer for the county, said work on the upgrade is continuing even without the two new towers — the proposed locations of which, he said, were chosen without adequate community input. The overhaul remains on schedule, he said, and is expected to be operational in two years.

“Those two sites are going to be delayed, but we don’t want to delay the operation of the system as a whole,” Kleine said. “We certainly would not change the sites if we felt like it was going to cause any kind of risk to public safety.”

He said the county has purchased additional equipment since the outage on May 10 and 11 to address the cause and stabilize the system.

Riemer and council Vice President Sidney Katz (D-District 3), who chairs the body’s public safety committee, wrote to Elrich last month, saying his decision to delay the two towers — a state tower at the Intercounty Connector and Georgia Avenue in Olney that the county would have shared, and another in Bretton Woods — has “strained” the system.

“I think it’s literally crazy we would delay replacing a failing public safety system,” Riemer said in an interview. “We need the county executive to reverse course here and follow through on the plan and get those towers up.”

Residents who have pushed for the new tower locations say they shouldn’t be blamed for the lags in implementing the new system.

“The county has been aware this system has been failing for a long time,” said Matt Quinn, president of the Greater Olney Civic Association.

Quinn said his group has been working with the county and the state to find a more acceptable location for the tower — and believes they have found one, just a short distance away.

State Sen. Benjamin F. Kramer (D-Montgomery) said community members were upset they hadn’t heard about the towers during the planning stages.

“Suddenly these neighborhoods were going to have a massive steel structure contiguous to their communities and you would have seen it anywhere you were,” Kramer said, adding that some residents also were concerned about possible health effects from the equipment. “It may have suited the needs of county and state government, but it doesn’t mean it’s an appropriate location for this kind of massive structure.”

Shanteé Felix, a spokeswoman for the Maryland Department of Transportation’s State Highway Administration, said that while the original Olney site is still “under consideration,” the agency is working on identifying “possible alternative sites.”

Dale Tibbitts, special assistant to Elrich, said alternative sites to the Bretton Woods tower are still being worked out.

“We do not discount the public safety component of this,” he said. “We think we’ve come up with a new way of dealing with these last two towers and keeping the rest of the system on track, on schedule.”

Meanwhile, the council’s public safety and government operations and fiscal policy committees plan to hold a joint hearing next month on the communications system.

Susan Farag, legislative analyst for the council, said the committees will seek information on options for alternative communications, how the system could operate with two fewer towers and whether there will be gaps in coverage as a result.

“We need to work together and we will work together to solve this concern,” said Katz, who also sits on the government operations committee. “The bottom line on this is we need to get something done.”

Lipp said another, smaller disruption occurred on Wednesday afternoon, when the normal 16 channels suddenly went down to just six. As the evening commute began, “all of a sudden we started getting ‘bonks’ again,” Lipp said.

He said it’s still unclear what caused that outage. “We don’t have confidence in any of this equipment,” he said. “It’s all antique stuff.”

Dan Morse contributed to this report.