A Massachusetts ambulance provider that has served a Greater Boston suburb for 25 years says it is “extremely disappointed” after city officials selected a new service company.

Armstrong Ambulance Service has described Medford’s decision to end its decades-long partnership with the provider as an unprecedented move, prompting concerns about the city’s transparency.

“In our 80 years of service across the Commonwealth, Armstrong has never lost an emergency medical services contract,” the service provider stated in a social media post earlier this week. “We were therefore extremely disappointed by the decision to sever our partnership with the City of Medford.”

Medford Mayor Breanna Lungo-Koehn and other officials announced that the city has entered into a three-year contract agreement with Cataldo Ambulance Service.

In their announcement the day before Christmas Eve, city officials highlighted how Cataldo will provide “all basic and advanced lifesaving ambulance emergency response coverage” beginning Jan. 19.

They added that the Somerville-based ambulance provider will be collaborating with the city to “assist with mental health and substance use emergency calls.” Cataldo is also set to provide new automated external defibrillators to the fire department and the city’s public schools.

Lungo-Koehn has emphasized how the new partnership will allow the city to better respond to “mental health and substance use crises with compassion, care, and the right resources.”

“One strong piece that Cataldo had, which is not common, is … a behavioral health unit,” the mayor told the Herald via phone on Wednesday. “That was a pretty exciting part of moving forward, being able to help residents who have mental health issues or substance abuse issues, who can get evaluated by the ambulance provider so they can avoid going straight to a hospital.”

Armstrong’s union EMTs and paramedics are pointing out how Lungo-Koehn and the city have not provided a public explanation for the decision to split ways with the company and an “opportunity for residents to weigh in.”

Teamsters Local 25, a union representing more than 150 Armstrong Ambulance professionals across the region, has said that the city informed the company on Dec. 21 that it would be switching to Cataldo.

In 2025, Armstrong averaged a response time of 4 minutes and 30 seconds in Medford, a city of roughly 60,000 people. Union EMTs and paramedics say that rate is “squarely within the National Fire Protection Association’s recommended 4 to 5 minute EMS/fire response window.”

“The mayor should not be gambling with public safety,” Teamsters Local 25 President Tom Mari said in a statement on Tuesday. “Armstrong Ambulance has provided first-class EMS services in Medford for more than 25 years. … Replacing a trusted provider without transparency or public input raises serious concerns for residents and first responders alike.”

Speaking to the Herald on New Year’s Eve, Lungo-Koehn reiterated that the city didn’t terminate a contract with Armstrong and that the last agreement with the company expired in November.

The mayor highlighted how the company met with city leaders, informing them that it wouldn’t be able to “honor” a part of the four-year agreement. She added that’s what prompted contract negotiations with a new service provider over the summer and into the early fall.

“I chose to negotiate with both Armstrong and Cataldo to keep leverage,” Lungo-Koehn said, “and to make sure that I got this city the best contract I could.”

The mayor declined to say what part of Armstrong’s contract the company couldn’t honor and explained that contracts longer than three years require City Council approval. Armstrong has four-year contracts, while Cataldo has three-year agreements, Lungo-Koehn said.

“Negotiations are under my purview,” the mayor said, “and I just ask and hope that residents of the city trust … how I handle negotiations. For this one, we had a team of five people, figuring out what was best for Medford.”

The City Council is slated to take action this week on a resolution calling for a “comprehensive review” of the ambulance contract negotiations and transition.

In a statement on Christmas Day, reacting to the city’s selection of Cataldo, Armstrong’s union EMTs and paramedics said the decision was made “without regard for the professionals who have protected this community for decades.”

“Many of us live in Medford,” the union stated. “We raise our families here. We respond to our neighbors’ worst days, and we do so with pride, professionalism, and deep commitment to this city.”