HUDSON, N.H. -- A Nashua man is in critical condition at Massachusetts General Hospital after suffering a serious head injury when police say he rode his bicycle into the side of a car at Wason Road and Flagstaff Drive on Monday.

Police said James Landry, 47, was riding a bicycle against traffic on Wason Road when a vehicle driven by Alisha McCoy, 30, of Nashua, went through a green light from Flagstone Drive to Wason Road.

Landry, who police say rode through a red light, struck the left front side of McCoy's vehicle and was thrown from his bicycle, according to police. Landry was not wearing a helmet and suffered a serious head injury when he landed on the ground, according to police.

When emergency crews arrived about 11:50 a.m., they found McCoy and other passersby attempting to care for Landry. Landry was transported by ambulance to Southern New Hampshire Medical Center in Nashua, and was later transferred to Massachusetts General Hospital in Boston, where he was listed in critical condition, according to police.

Police said McCoy will not face charges.

"The Hudson police would like to remind bicyclists to always wear a helmet and always obey the rules of the road," police said in a press release. "Ride with traffic, not against it, and stop at traffic lights and stop signs."