BOSTON (CBS) – Two bicycle accidents on Boston streets in four days has the cycling community on edge.

The latest incident happened in South Boston when a tractor trailer and a bicyclist both took a turn from A Street onto West Broadway at the same time. That’s when they collided.

A tearful Kelly Yeo described what she saw when she just happened to be walking by. “I guess they were going in and out of traffic and the tractor trailer was turning and he didn’t see her, and he just dragged her, and now her head’s under the tire,” she says.

WBZ NewsRadio 1030′s Bernice Corpuz reports

Police say the victim was a woman in her 30′s with ties to South Boston. The driver is not facing any charges at this point. “We’re scanning the entire area for video,” says Boston Police Supt. Bruce Holloway.

It happened on the same day a Dorchester man, Michael Ahern, was in court facing a list of charges including motor vehicle homicide and drunk driving. Police say his pick-up truck hit and killed a 63-year-old Dorchester man Friday just after midnight.

Bostonbiker.org, a group that advocates for biker safety, posted on its website. “Another in a series of horrific and tragic events. We must do better at protecting cyclists.”