One of San Francisco’s most dangerous streets for cyclists and pedestrians claimed another life Friday morning when a Berkeley woman riding a bike was run over by a truck in the city’s South of Market neighborhood, prompting city officials to call for swift action in implementing safety measures.

The collision was reported around 8:30 a.m. near the intersection of Howard and Sixth streets, according to the San Francisco Police Department. Howard Street was identified by the San Francisco Municipal Transportation Agency as part of the city’s “High Injury Network,” which consists of roadways that pose the most risk.

San Francisco medical examiner’s officials identified the bicyclist Friday night as 30-year-old Tess Rothstein.

Twelve percent of San Francisco streets “account for 70 percent of San Francisco’s severe and fatal traffic crashes,” according to Vision Zero, an initiative initiated by SFMTA seeking to create safer streets and eliminate all traffic deaths.

So far, five people have been killed in 2019 due to traffic-related incidents, according to Vision Zero. Three people were killed while walking and one person was killed while driving, according to the latest city figures. The woman’s death Friday brings the year’s total to five.

Mayor London Breed called the death “heartbreaking,” and she noted that immediate action will be taken in making changes to the road.

“There are long-term safety improvements coming to Howard Street, and I am pushing to move those forward as fast as possible,” Breed said. “But while we wait for these capital improvements, we need to make short-term safety enhancements, which I have instructed SFMTA to do without delay.”

The transit agency started the Folsom-Howard Streetscape Project in 2016 to redesign the two streets that run parallel with one another to make it safer for cyclists and pedestrians. For cyclists, the project will create concrete buffers for parking-protected bikeways, new concrete protection for bicyclists at intersections, more traffic signals with phases for cyclists and turning vehicles, and raised bikeways in certain alleyways.

The efforts will focus on Howard Street between Third and 11th streets, and on Folsom Street between Second and 11th streets. In 2018, two people were killed on Folsom and Howard streets, SFMTA reported.

The agency has already made some improvements to Sixth Street, including painted safety zones and new mid-block crossings and traffic signals, said Paul Rose, SFMTA’s spokesman. Protected bike lanes were installed and a red zone was implemented on the corners of Howard Street between Sixth and 11th streets to ensure that people in cars have a better view of pedestrians and cyclists.

“The original timeline for Sixth Street was for construction to start in 2020, and we are exploring options to install improvements as fast as possible as part of the new directive from the mayor,” Rose said.

The agency also plans to finish installing a protected left-turn lane in May from Howard to Sixth Street to separate pedestrians from turning vehicles, Rose said.

On Friday, the scene of the collision was somber as dozens of people watched police investigate.

Dexter Greene, 38, of San Francisco, was grabbing his wallet from his friend’s vehicle near the scene when he saw a woman’s body get thrown from under a truck. He immediately started yelling at the driver to stop.

“I saw her just come out of the back tire,” Greene said. “I yelled at the box truck, ‘Hey, you guys hit that girl, you ran her over.’”

The driver of the truck then stopped and got out of the vehicle, he said.

“He saw her and put his hand over his mouth,” Greene added.

Next to a black bike, a yellow sheet covered the body of the woman. The truck was parked less than 10 feet away from her.

Rob Divino, 66, had just come outside to walk his dog when he saw the woman’s body on the ground. She was wearing a helmet, he said, but it appeared her body had been crushed by the weight of the truck.

“It was just horrible,” said Divino, a San Francisco resident. “These people drive down Howard Street like they have no conscience. They drive quick. It’s a problem.”

The driver of the truck stayed at the scene and was cooperating with authorities, said Officer Robert Rueca, a San Francisco police spokesman.

“We haven’t determined what the cause of the collision is at this point,” he said.

Authorities were on scene investigating the incident.

Howard Street between Fifth and Sixth streets was shut down for nearly five hours.

“We know this time of the morning, it is already congested,” Rueca said.

After the fatal collision Friday, District Six Supervisor Matt Haney tweeted that there should be a protected bike lane on Howard Street. He said he would work with the San Francisco Bike Coalition for “immediate safety improvements.”

“It’s heartbreaking,” he said. “We have to do so much better to protect cyclists and pedestrians.”

Chronicle staff writer Lauren Hernández contributed to this report.