20 years ago Tuesday, a fire in a vacant storage building in Worcester claimed the lives of the six firefighters. The so-called Cold Storage fire resonated around the country, leading to new protocols for fighting fires and rallying Worcester residents around the department.

"I came on the job with Paul,” Bongivio said. "Jerry, out of training, came to the Providence Street Fire Station. Tommy I worked with, great guy. Jay I didn't know as much. Joe McGuirk, I know his wife very well and his family ... Of course, Timmy. Yeah, I knew them all. Fantastic people. Heroes."

He walked toward an old pair of firefighter gloves used in the blaze, framed with the pictures of the six who gave their lives: Thomas Spencer, Paul Brotherton, Timothy Jackson, Jeremiah Lucey, James Lyons, and Joseph McGuirk.

Bongovio was on duty at the Worcester Historical Fire Society’s exhibit to greet visitors and answer their questions. The room is filled with posters made by school kids thanking the department, patches and caps sent in from firefighters around the country, and memorabilia salvaged from the burnt ruins of the Worcester Cold Storage & Warehouse Co. building.

"I guess 20 years is the time to break all this stuff out again and show the people. And the people still support us,” said Angelo Bongovio, a Worcester firefighter from 1983 to 2011.

A crowd of people lined up on one end of Worcester's Union Station one recent Sunday morning. They were there to see a special exhibit commemorating the Worcester Six.

Investigators found that the fire was started accidentally by two homeless people squatting in the vacant warehouse. Firefighters entered the building after hearing there may have been people inside — that turned out to be false. The labyrinthine layout, and the lack of windows, left the rescuers disoriented and calling for help.

Fire Lt. John Sullivan was among those who went in to search for them. He said the rescue was particularly difficult because commanders didn’t know where to send the teams. It was only after the fire that they learned which floor the trapped firefighters were on — and how close they were.

"We actually got called to the fifth floor,” said Sullivan, who’s now chief of the Brookline Fire Department. "So we were on the right floor, but at that point, conditions were such that leaving the stairwell was not tenable ... We were on the stairwell trying to sound for them to get them out. And as we were doing that, the chief called for the evacuation of the building."

A row of firefighters form a line to remove debris from the fire-gutted Worcester Cold Storage building in the search for the missing firefighters Tuesday, Dec. 7, 1999. (AP photo courtesy Worcester Telegram & Gazette)

Sullivan says the Cold Storage fire was the defining event in his career, taking him around the country and beyond to participate in seminars on firefighter safety and well-being.

"Personally, it's been a huge burden for many years for me,” he said. "I've tried to hold it up as best I can for my family and for the firefighters around me — in my personal times, you know, I've had my my moments."

The Cold Storage fire investigation resulted in a series of recommendations to try to prevent firefighters from getting lost in burning buildings. They include attaching ropes to entry points, setting up high powered lights, and using thermal imaging cameras to spot people through the smoke and haze.

Pictured from top left clockwise are firefighters Joseph McGuirk, James Lyons III, Jeremiah Lucey, Paul Brotherton, Lt. Thomas Spencer and Timothy Jackson as displayed in the Worcester Fire Department's Grove Street station in 2001. (Charles Krupa, AP)

Rich MacKinnon, head of the Massachusetts firefighters union, said the biggest mark left by the blaze was the establishment of so-called "RIT companies," rapid intervention teams, across the state.

“When a firefighter does get in a situation where they do get disoriented and they do need help, that we have that [RIT] team specially trained, ready to go with special equipment to get that firefighter,” he said.

But events in Worcester over the last 20 years show that no matter what kind of protocols or equipment are in use, it will always be a dangerous job.

“For many of us, it's the only thing we've ever wanted to do,” MacKinnon said.

"You have to always honor and never forget the members that you've lost and their families. But at the end of the day, there's another fire, there's another call to answer — members will always be there to answer those calls."

Some of an estimated 30,000 fire and public safety personnel who marched in memory of the Fallen Six as part of ceremonies held Dec. 9, 1999. (Neal Hamberg/AP)

President Clinton puts his head in his hands as he sits with Frank Raffa, president of the Worcester Firefighters Union, far right, and an unidentified clergyman during the 1999 memorial service. (Stephan Savoia/AP)

Three Worcester firefighters have been killed in the line of duty since the Cold Storage blaze — most recently Lt. Jason Menard, who died last month died after entering a burning building.

Over at the Worcester Flea Market, vendor Susan Mastromatteo swiped her cellphone as she ticked off prices to customers.

For ordinary Worcester residents like Mastromatteo, the Cold Storage fire is never far from mind.

"I knew most of them,” she said, choking back tears. “We knew most of them. One was — my nephew's father was the kid's friends ... Nobody in Worcester doesn't not know anybody … so it’s hard."

One of Mastromatteo's nephews is a firefighter — another nephew is a police officer — and she says it’s the bravery of the city’s first responders that inspires young people to serve.

Thousands of people are expected to gather Tuesday evening at the site of the Cold Storage fire --where a new fire station now stands — to remember the six men who gave their lives to keep others safe.

The monument dedicated to the Worcester SIx now stands at the site of the Worcester Cold Storage & Warehouse Co. building. The land is now home to a fire station. (Simón Rios/WBUR)

Part of the memorial dedicated to the Fallen Six in Worcester. (Simón Rios/WBUR)

Correction: An earlier version of this post incorrectly described the genders of the two people who accidentally started the fire. The post has been updated. We regret the error.