After a truck struck and killed cyclist Louisa Gag, the outpouring of grief was immediate from scores of friends, fellow activists, and City Hall co-workers — including Mayor Michelle Wu, for whom Gag had been an intern years ago.
But a week later, there is still very little known about the circumstances of her death.
City Hall remains reticent to provide details: How the crash happened, the name of the driver, and owner of the vehicle are among the major facts that remain undisclosed. Meanwhile, transit activists who knew Gag continue to criticize Wu, questioning her administration’s recent steps to remove protective barriers from some bike lanes and slow-walk other projects, as well as the lack of progress on its own plans for safety improvements near the intersection with Tremont Street where their friend died.
In response to multiple questions on Wednesday morning, Wu deferred to the ongoing investigation, saying she didn’t want to release any information that could jeopardize it.
“We need a full, transparent, comprehensive investigation about the facts of exactly what took place and what needs to be done to make sure that this never happens again,” Wu told reporters when pressed. “I know as soon as they are able, the appropriate authorities will share updates with Louisa’s family and with the general public.”
Boston police released a few more details Wednesday afternoon, specifying that the truck is a construction vehicle, specifically a Peterbilt 389 tractor trailer. Both the truck and Gag were traveling eastbound on Tremont approaching Parker Street when the truck “made contact” with Gag near the corner of the two streets.
Suffolk DA Kevin Hayden’s office said the investigation “will be comprehensive and will incorporate all aspects of the incident.”
Asked about why her Police Department isn’t putting out more information, Wu said, “I know as soon as they are able, we will make sure that they are sharing information with the public and with Louisa’s family.”
The 36-year-old Gag, an activist turned City Hall transportation planner, had worked for years trying to make Boston safer for cyclists and pedestrians only to become a victim of the very streets she was working to improve.
She was struck near the corner of Tremont and Parker streets near the Roxbury Crossing MBTA stop last Thursday. In the immediate aftermath, police gave a brief statement and released a short incident report.
Boston police first said they responded to a report of a pedestrian struck, though by the end of the day they clarified it was a cyclist. Police said emergency personnel pronounced the victim dead at the scene, and that the vehicle involved in the crash “has stopped.”
Later that day, the mayor wrote about Gag in a social media post in which she mourned her death and talked about her activism.
Investigations involving traffic crashes can take months. It took nearly one year for an investigation to conclude in criminal charges against the man accused of striking a child with a school bus in Hyde Park last year, though authorities released more information such as the name of the driver within a few weeks.
When a cyclist was struck and killed in September 2024 in Cambridge, State Police quickly released some general information about the mechanics of the crash — that the driver had lost control — though the investigation didn’t conclude until the following spring, when authorities filed criminal charges.
Gag’s family referred comment to lawyer Joshua Zisson, a local personal-injury attorney who focuses on cyclists. He declined to comment.
Gag grew up in Roslindale, graduated from Boston Latin School and earned degrees at the University of Rochester and Tufts University. She “worked tirelessly to improve the city she loved, devoting herself to making it more livable, enjoyable, and humane,” according to her obituary.
Hundreds attended a vigil for Gag on Sunday at Adams Park in Roslindale, and another memorial is planned by various bike groups for Thursday night at City Hall Plaza.
On Wednesday, Wu said, “We are devastated at tragic loss of someone who worked so hard and so brilliantly to ensure that the city of Boston would be a more vibrant and beautiful and welcoming, accessible space for everyone.”
The area of the crash has been a source of concern and frustration for cycling safety advocates in recent years. That section of Tremont has a painted bike lane as it approaches Parker Street that then transitions to a dotted line roughly 70 feet from a crosswalk.
Advocates have pointed to a 2023 city document relating to planning for an area around Parker Street that includes its intersection with Tremont. The presentation is largely focused on side streets rather than busy Tremont, but it still identified the stretch of Tremont as having “poor biking conditions.” It highlights that stretch in red, indicating the highest of four levels of “traffic stress” with bicycles.
Wu has said street safety remains a priority for her administration, and emphasized that work on many such infrastructure projects is ongoing. Wu’s office said last week the location of the crash was not covered under the Parker Street-area planning process and that there never were plans for a protected bike lane there.
Stacy Thompson, a transportation advocate who worked with Gag for years, said it’s not clear whether any particular proposed project would have directly affected driver or cyclist interactions on that stretch.
“We don’t know those answers yet,” Thompson said, adding that she looks forward to the police resolving a thorough investigation and providing more information.
But, she said, “That area has never been particularly comfortable and safe” for pedestrians or cyclists.
In 2025, there were 256 crashes in Boston that resulted in a cyclist being injured, according to the city’s “Vision Zero” database, which relies on data from Boston Emergency Medical Services. No fatalities were reported. Data on crashes involving cyclists in the city this year was not available.
The tragedy occurred during a time when some transit advocates have criticized Wu for stalling a number of street projects they said would improve public safety. One such area that’s been targeted for improvement is the busy intersection at Roxbury Crossing, a few blocks from the crash scene.
“The projects in and around that area would have changed driver behavior just generally,” said Galen Mook, executive director of MassBike.
Sean Cotter can be reached at sean.cotter@globe.com. Follow him @cotterreporter.