A car slammed into a group of bicyclists Saturday during an annual ride along the New England coastline, killing two riders and injuring two others, police said.

The crash happened on a two-lane bridge in Hampton at about 8:30 a.m., just after the start of the 40th annual Granite State Wheelmen Tri-State Seacoast Century ride.

Police said two Massachusetts women were killed. They were identified as Pamela Wells, 60, of South Hamilton, and Elise Bouchard, 52, of Danvers. Two other riders, Uew Uhmeyer, 60, of Essex, Mass., and Margo Heigh, 52, of Danvers, Mass., suffered non-life threatening injuries, police told MyFoxBoston.com. They were treated at a hospital and released. 

Investigators said a 20-year-old motorist was driving southbound and crossed into the northbound lane, hitting the riders. The driver has been identified as Darriean Hess of Seabrook, N.H., MyFoxBoston.com reported. 

Authorities haven't said whether the driver will be charged. Hampton police Deputy Chief Richard Sawyer said the investigation is ongoing and could take some time while police interview witnesses.

Event organizers didn't immediately return messages seeking comment. A section of Ocean Boulevard, also known as Route 1A, was closed off while police investigated the crash but reopened around 2 p.m., Sawyer said.

"The car just plowed right into them, just went right into them on the wrong side of the street," Michael Costello, a witness to the crash told MyFoxBoston.com.

"It was pretty gruesome," he said. 

Sawyer said riders had to be routed around the bridge closure while police investigated.

The route typically follows the Massachusetts, New Hampshire and Maine coastlines, according to the event's website.

The event included rides of up to 100 miles on Saturday and Sunday. Riders were encouraged to follow all the rules of the road as they encountered narrow colonial New England roads, steel decked bridges and weekend traffic, according to the event's website.

The ride is organized by Granite State Wheelmen, a bicycling club.

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The Associated Press contributed to this report.