Boston — In the wake of two pedestrian fatalities, including the death of a 4-year-old girl, over the past week, the Boston City Council plans to explore a citywide reduction of the speed limit from 25 to 20 mph to enhance street safety.

The city last lowered its default speed limit, from 30 to 25 mph, in 2017, but councilors have pushed for a further reduction to 20 mph in the past, according to a hearing order put forward by Ed Flynn, discussed on Wednesday, that is renewing the past debate following the recent fatalities involving a child and wheelchair user.

While he’s pushing for a new 20 mph speed limit throughout Boston with enhanced traffic enforcement by the city’s police department, Flynn said he thinks the new limit should be even lower, at 15 mph.

“I continue to believe that pedestrian safety is one of the most critical issues we face in the city of Boston,” Flynn said at the Wednesday meeting, referencing the city’s goal for Vision Zero, or having zero serious and fatal traffic crashes.

“In Boston,” he said, “25 mph is excessive driving through a dense neighborhood. I think it should be 20 mph. I even think it should be 15 mph, but driving 25 mph on residential streets is unhealthy. It’s unsafe.”

He pointed to places where the Council’s past advocacy for a 20 mph speed limit has already been implemented, via a Safety Surge Program the city incorporated last year, that installed speed hump zones with that lower limit on qualifying neighborhood streets to make them safer for pedestrians.

“However, the speed hump program is only being installed on smaller side streets, but not on wider and busier streets where cars and commuters are consistently speeding and serious crashes also occur,” Flynn said.

Main streets, commercial roads and high traffic corridors are also dangerous for pedestrians, and would benefit from similar traffic-calming infrastructure “to force vehicles to slow down,” he said, noting that councilors should consider pushing for updates to the city’s Safety Surge Program to reflect those changes.

Boston should also consider experimenting with electronic technology that is designed to automatically slow speeding cars down to whatever the designated speed limit is, whether it be 25 or 20 mph, which, Flynn said, is already being tested in other cities across the country.

His suggestions were met favorably by other councilors who signed onto a hearing order he filed to discuss pedestrian safety, traffic calming and expanding the Safety Surge Program in response to the two pedestrian fatalities that occurred in his district over a roughly week-long period.

On Tuesday, a 57-year-old man in a wheelchair, Fernando R. Pizzaro, was struck and killed by a cement truck driver in the area of Frontage Road and Traveler Street in South Boston.

Councilors were particularly troubled by the death that occurred Sunday, March 24, when a 4-year-old girl, Gracie Gancheva, was struck and killed by a truck at the intersection of Congress and Sleeper streets, in the Fort Point neighborhood of Southie near the Boston Children’s Museum.

“I think of my own 4-year-old child and that’s nightmare-scenario stuff,” Councilor John FitzGerald said.

The worst part of those tragedies, FitzGerald said, is they’re “so preventable,” in terms of whether the driver is paying attention or texting and driving.

He’s calling for the Wu administration to work with the City Council to put together a list of the 15 “biggest perpetrators” of speeding in each district, to pinpoint where the worst streets are and prioritize those for safety improvements.

The city had already been targeting long-term pedestrian safety upgrades at the Fort Point intersection where Gancheva, the young girl, was killed, and is now working to make temporary upgrades in response to the fatality.

Flynn joined the city’s Chief of Streets Jascha Franklin-Hodge at the intersection last Saturday to commemorate the death and discuss the resulting temporary upgrades, ahead of a larger construction project set to get underway early next year.

The two fatalities bookended the release of a new report from WalkMassachusetts that stated Boston had the most pedestrian fatalities last year, accounting for eight of the 69 pedestrians who lost their lives in crashes in the state.

City Council President Ruthzee Louijeune echoed her colleagues in elevating the names of the pedestrians who were recently killed while also calling attention to the death of a 4-year-old boy Ivan Pierre, who was killed in a hit-and-run crash last year in Hyde Park, where she lives.

“No parent should have to bury their child,” Louijeune said. “If there’s anything that should drive policy change, it’s when parents have to bury their young kids. Few things have struck me as much as the funeral of Ivan Pierre because a 4-year-old dying should not be happening in our streets.”

The hearing order was referred to the planning, development and transportation committee for further discussion.