The teen -- who was not wearing a helmet -- was riding his bicycle down William Street and went through a stop sign at Dale Street at about 3 p.m., Sgt. Kelly Connelly said.
A motorist driving westbound on Dale Street couldn't stop in time and hit the bicyclist, Connelly said.
Initially, the teen's injuries didn't appear to be serious, she said.
"At the scene, he was conscious and alert, and the only injuries he had were to his leg and a cut to his head," Connelly said. "He was treated and examined, but then at 6 p.m. [Wednesday] night the hospital called here to say the boy had a brain bleed and he was being taken to Yale-New Haven Hospital via helicopter."
There was no further information available on the teen's condition, Connelly said Thursday afternoon.
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