A female pedestrian suffered life-threatening injuries in a collision with a bicyclist near Kenmore Square in Boston on Tuesday morning, according to police. The incident occurred at 9:09 a.m. near the intersection of Commonwealth Avenue and St. Mary’s Street, a police spokesman said.

Both the pedestrian and the cyclist were transported to local hospitals for treatment. While the pedestrian’s injuries were reported as life-threatening, the bicyclist’s condition was not believed to be serious.

Witness Ashley Zeissler, a 20-year-old Boston University junior, was nearby at the time of the crash. She recalled hearing the impact despite music playing through her headphones and seeing the pedestrian fall into the adjacent traffic lane. Zeissler noted that the bicyclist was not in the designated bike lane and observed that the pedestrian appeared young with an injured arm, unconscious and shaking. Passersby quickly intervened to assist her and called emergency services.

Authorities have not confirmed whether the pedestrian is affiliated with Boston University. In the aftermath of the crash, police restricted pedestrian and vehicular movement around the scene. By 11:15 a.m., Commonwealth Avenue near the St. Mary’s Green Line stop was partially closed, with tapes blocking off sections of the roadway.

Boston University issued an emergency alert to students and faculty at 11 a.m., stating the university was responding to a traffic accident at the intersection. The alert assured the community that there was no ongoing threat but warned of traffic disruptions lasting for several hours.

Police later expanded the secured perimeter as members of a fatal collision investigation team arrived to gather evidence and take measurements. Eastbound traffic was limited to a single lane during the investigation. By 1:10 p.m., Boston University Police announced the scene had been cleared.

At the site, officers inspected a black-and-silver Bianchi road bicycle found propped against a police vehicle, with a helmet hanging from its handlebars. The bike was later laid on its side for detailed photographing as part of the investigation.

The Boston University Office of the Dean of Students issued an email expressing support for the individuals affected by the incident and directed the university community to available crisis counseling and psychiatric resources. Officials underscored the importance of safe travel practices, urging everyone—whether walking, driving, or using bicycles, e-bikes, skateboards, or scooters—to remain vigilant and considerate of others’ safety.

Boston police are leading the investigation with assistance from the Boston University Police Department.