A bicyclist suffered serious head injuries Monday afternoon when she was thrown from her bike in a collision with a pickup truck at the intersection of Rowland Road and Paulding Place.

The cyclist -- Betty Lucas, 68, of Fairfield Beach Road -- was reported to be in "critical" condition Tuesday at Bridgeport Hospital, where she is being treated for what officials said were traumatic head injuries.

Lucas, who police said was not wearing a helmet at the time of the accident, had no identification in her possession at the time of the 3:30 p.m. accident other than a cellphone and a Stop & Shop discount card, said police Lt. James Perez. Investigators used those devices to determine her identity later in the day.

It initially appeared the driver of the pickup stopped at the intersection's stop sign before proceeding, Perez said. The driver told police he did not know what direction the bicyclist was headed when she suddenly appeared and collided with the truck.

Two members of the police accident reconstruction team remained at the crash scene later Monday trying to determine how the crash occurred.