The duck boat Penelope Pru was stopped at a red light on Charles Street waiting to head up Beacon Hill with a load of tourists on board. Just ahead, also waiting to turn, was a motor scooter with two riders out to enjoy the crisp spring morning.
It was a familiar Boston scene. Then the light, and everything, changed.
“The duck boat just took off and actually went into the back of the people on the scooter,” said Graham Foster, recounting the scene that unfolded before him around 11:30 a.m.
The scooter operator tried to accelerate, Foster said, but could not get out of the duck boat’s way in time. He said witnesses yelled at the duck boat operator and tried to alert him.
“The [scooter] flipped on the side and the next thing you know [the duck boat] ran right over [the scooter],” Foster said.
When the duck boat finally came to a stop, the 29-year-old woman operating the scooter and the man riding with her were on the ground behind the magenta amphibious vessel.
The woman was rushed to Massachusetts General Hospital, where she died, Boston Police Commissioner William Evans said. The man was not seriously injured; both were wearing helmets, he said.
“It looks like a terrible tragedy,” Evans said.
The crash led to a daylong investigation that unfolded as thousands came across the gruesome scene. The scooter was crushed under the driver’s side front wheel of one of the vehicles that give tours and have become synonymous with parades for the city’s championship-winning sports teams.
Foster, who lives in Norton, said the man and woman were not moving after falling to the ground.
The duck boat operator stopped the vehicle, he said.
“He realized he had run over something and stopped and was getting off the bus in a panic,” Foster said. “It was very horrible.”
Evans said none of the 26 to 28 people aboard the duck boat was injured.
Boston police loaded the passengers onto a second duck boat and escorted them to police headquarters to be interviewed, Evans said. The driver was also taken from the scene for questioning, he said.
The collision occurred near a city-owned surveillance camera. Officer Rachel McGuire, a Boston police spokeswoman, said investigators are reviewing surveillance footage.
“We’ll have to determine whether criminal charges have to be taken out against the operator,” Evans said.
The names of the victim and the duck boat operator were not released Saturday.
Bob Schwartz, director of marketing and sales for Boston Duck Tours, said the driver “has been with the company for years and has a great safety record.”
The company, which has been operating since 1994, was never before involved in a fatal accident, Schwartz said.
In a statement Saturday, the company said, “The thoughts and prayers of the Boston Duck Tours cast and crew are with the victim’s family following today’s tragic accident. . . . Safety is of the utmost importance to our company, and we will continue to provide our cooperation to the authorities.”
Another witness, Jay Beausang, said he was planting a tree at the intersection of Beacon and Charles streets when he saw a person tumble from a scooter and land . Scraping sounds followed, he said.
“A body popped out the back of the duck boat,” said Beausang, the owner of Westwood Nurseries. “I ran over. I got on my knees, held her wrist for a pulse.”
Boston Police Sergeant Brian Waters, who was working a detail nearby, also rushed to the woman’s side, telling her again and again, “We’re going to help you,” Beausang said.
The woman tried to talk but was unable to speak, he said. She was not bleeding, Beausang said, but looked like a “rag doll.” He said the man who was also on the scooter told the woman she was going to be OK.
“I didn’t say anything,” said Beausang, who lives in Norfolk. “I just held onto her wrist, felt her pulse fade away.”
Beausang said he was interviewed by Boston police, who told him the man and woman were on their first date. McGuire said she could not confirm that account.
Beacon Hill resident Morgan Ralph said passengers aboard the duck boat appeared stunned as they watched rescuers perform CPR.
“They were all sort of huddled in the back of the duck boat peering down,” said Ralph, who was out shopping when he witnessed the aftermath of the crash.
A section of Beacon Street was closed until about 5:30 p.m. For hours, a pair of women’s shoes and two helmets sat in the street, one behind the duck boat and the other next to the vehicle.
Officers put evidence markers down and placed items in paper bags.
Before an ambulance took the woman away, Ralph said he saw a man standing in the street watching rescuers trying to help her.
“He was looking down, sort of emotionless, blank, sort of shocked,” Ralph said.
He was holding a helmet.
As dusk fell at the crash site, a friend of the victim’s stood next to a box of flowers he purchased to honor the woman.
Ethan Crain, who lives in South Boston, declined to provide the woman’s full name, but said she lived on Beacon Hill and enjoyed riding her scooter in nice weather.
“She had all the greatest qualities a human being could have,” Crain said. “She possessed all that was kind, compassionate, smart, caring, and considerate.”
Crain said he met the woman through work. She had worked in the insurance industry and volunteered at a women’s shelter in Boston, he said.
Crain said he last saw the woman Sunday and they exchanged text messages Friday night. She told him she planned to spend Saturday with her sister.
“I was very fond of her,” Crain said. “She was incredibly poised and full of life. I feel so bad for her family.”
Globe correspondent Mackenzie Cummings-Grady contributed to this report. Laura Crimaldi can be reached at firstname.lastname@example.org. Follow her on Twitter@lauracrimaldi.