A 91-year-old woman died after being hit by a cement truck in San Francisco’s Lower Pacific Heights neighborhood Thursday afternoon, marking the city’s fourth pedestrian fatality of the year, police said Friday.

The victim, whose identity has not been released, had been crossing Fillmore Street mid-block north of California Street when the northbound truck driver hit her around 3:15 p.m., said police Sgt. Eric Mahoney. She was transported to San Francisco General Hospital, where she underwent surgery, but later died from her injuries, police said.

Investigators found that the truck driver, who stayed at the scene and cooperated with officers, was not at fault, Mahoney said. The driver had just crossed through the intersection at California Street when he came to a stop behind a couple of other vehicles, according to police. As the other vehicles started moving again, the woman stepped in front of the truck and was hit.

Less than a day earlier, a 15-year-old boy was hurt while crossing Sunset Boulevard at Yorba Street, the same intersection where 78-year-old Isaak Berenzon was killed this month.