A 35-year-old woman fell in the middle of a St. Paul street and was fatally run over by a teenage motorist as bystanders tried to help her, authorities said.

Witnesses saw the woman, identified Wednesday afternoon as Karina R. Chosa, of St. Paul, fall about 6 p.m. Tuesday just east of the intersection of W. George Street and Stryker Avenue. As they tried to help the woman, a motorist heading west on George Street approached, police said.

"When it appeared that the driver was not slowing down, the good Samaritans moved out of the roadway and away from the woman to avoid being struck," said police spokesman Steve Linders. "That's when the approaching vehicle struck the victim."

Paramedics took Chosa from the West Side intersection to Regions Hospital, where she died. Linders said it was unclear why Chosa was in the road.

Chosa's sister, Joanne Chosa, said Wednesday that "we have no idea why she was on the West Side" soon after being dropped off by her brother earlier in the day at her home in a different St. Paul neighborhood.

The driver who struck the woman, a 16-year-old St. Paul boy with a valid driver's license, had a green light as he went through the intersection, Linders said. He stopped and called 911, and he has been cooperating with police, Linders said.

Preliminary information gathered at the scene indicated he was not impaired by drugs or alcohol.

Joanne Chosa said her sister leaves behind three children: Gabriel, 9; Keyara, 8; and Lily, 5.

"She was trying to get her life together!!" the sister said in a posting on a GoFundMe campaign started to help with funeral expenses. "She was struggling so hard with mental health issues!!"