PORT CLYDE — A New York City woman who was the driver of a car that plowed into people and cars on a Port Clyde wharf Sunday afternoon does not know what happened, according to the Knox County Sheriff’s Office.

The crash killed a 9-year-old boy from Massachusetts and seriously injured his 50-year-old mother and 6-year-old brother. Both remain at Maine Medical Center in Portland. The victims’ names are not being released until the department knows that all family members have been notified, Chief Deputy Tim Carroll said.

Jonathan Coggeshall, 68, of Port Clyde, who also was hit by the car, is hospitalized at Pen Bay Medical Center in Rockport with a hip injury.

Sheriff Donna Dennison said the driver of the car, Cheryl Torgerson, 61, was taken to Pen Bay Medical but was not seriously injured. Torgerson underwent a blood test, which is a routine procedure in a fatal crash, the sheriff said. There was no indication that Torgerson was under the influence of anything, the sheriff said.

Torgerson said she does not recall what happened other than the car sped up, Carroll said. The accelerator was down, he said.

Dennison said the woman appeared to be in shock.

Torgerson’s car has been impounded and will be taken to a secure storage facility in Warren until Maine State Police Trooper Chris Rogers can inspect it to determine if there was a mechanical problem with the Infiniti.

The accident occurred at 2:45 p.m. Sunday while Torgerson was traveling south toward the ferry wharf and parking area. The woman told police that she was going to get on the ferry to Monhegan. The Infiniti then accelerated, struck a car and spun it around, then struck the Port Clyde man and pushed him into a building where crafts are sold, Carroll said.

The car then continued on and struck five other vehicles parked at the dock and the Massachusetts family, who had just arrived to get on the ferry for a two-week vacation on Monhegan. The children’s father was still in the family’s van and witnessed the crash.

Rescue staff worked on the 9-year-old boy at the scene but he died on the way to the hospital, Dennison said.

Two LifeFlight helicopters landed at a town ballfield near the scene to airlift the mother and younger son to Portland.

Carroll said the scene was a difficult one for responders.

“I have a 9-year-old son. It makes you think and appreciate what you have,” he said.

There will be a debriefing for all personnel who went to the crash scene, Carroll said, and a counselor will be on hand. The sheriff said a pastor also will be invited to attend.

“A pastor can offer comfort at times like this,” she said.

Carroll said officers were at the scene past 9 p.m.

A member of the Kennebec County Sheriff’s Office is working with the Knox County Sheriff’s Department to map out the sequence of the crash.

Members of the St. George Emergency Medical Service, St. George Fire Department, South Thomaston Fire Department and Rockland Emergency Medical Services went to the scene.

Dennison praised the St. George crew for its quick response and its efforts in the aftermath of the crash.