A sheet covers the body of a 23-year-old bicyclist killed at the intersection of Commonwealth Avenue and St. Paul Street Thursday morning. (Jesse Costa/WBUR)

Update at 4:25 p.m.: Boston University has identified the bicyclist killed in the accident as Christopher Weigl, a 23-year-old graduate student who was pursuing a master’s in photojournalism. (See his photo website.) It's Boston’s fifth cyclist death of the year.

"He was one of the best graduate students I’ve had here; he took responsibility for all of his work and met every deadline," senior lecturer Peter Smith told BU Today. "He was the kind of student you hope for.”

Weigl grew up in Southborough and earned his bachelor's degree from Skidmore College. BU Today has more on his academic pursuits and a video student profile.

Christopher Weigl (Student profile screenshot)

Earlier post with updates:

Boston Police are investigating after a Boston University student on a bicycle was struck and killed by a tractor trailer at the intersection of Commonwealth Avenue and St. Paul Street just after 8:30 a.m. Thursday.

The victim, described by police as a 23-year-old male, was pronounced deceased at the scene. Police have not yet identified him, pending family notification.

BU President Robert Brown confirmed that the victim was a student in a letter to the school community.

Witnesses said the cyclist was in the bike lane when he collided with the truck as it turned right from Commonwealth onto St. Paul.

"He was going pretty fast down the street, and the truck was taking a left-lane right turn down to St. Paul Street," said CVS employee Stanley Brown, who witnessed the collision. "And I just hear a smack and then I see the guy getting run over by the wheels."

Police said the operator of the truck remained on the scene as officers responded. "No citations have been issued at this time," police added.

A Boston University student riding his bicycle was killed in Allston last month after he was hit by an MBTA bus.

BU's Brown addressed the two student bicyclist fatalities in his letter:

As most of you know, this is the second fatal bicycle accident in our community this fall. We are very concerned about the dangers faced by members of our community who must navigate the streets on and near our campus, especially bicyclists and pedestrians. As we identify ways in which education and changes in practice can reduce risks, we will take all necessary and possible steps to do so.

He added that counseling for those affected by Thursday's accident and its aftermath will be made available by the university.

Boston city councilors had previously scheduled a hearing on bike safety for Thursday afternoon. Councilor Felix Arroyo, who rode his bike from his home in Jamaica Plain to City Hall Thursday morning to raise awareness for bike safety, said the accident emphasizes the need for greater awareness.

"This person's not the first person to lose their life in the city of Boston while cycling," Arroyo said. "Which is why we need to make sure our roads are safe for everyone who uses them."