A South African singer was allegedly sexually harassed by her Uber driver in her driveway. The singer, Nikki Williams, posted an update about the incident to her Twitter account. Uber suspended the driver and apologized for the incident, according to Mashable. “Just reported my Uber driver for sexual harrassment. He tried to grab & kiss me in my own driveway. Fought him off and ran inside,” Williams tweeted on Saturday.

“Uber has zero tolerance for this behavior, and we apologize to Ms. Williams for this terrible experience. We immediately deactivated the driver, and have begun an investigation,” Kaitlin Darkish, an Uber spokesperson, told Mashable on Saturday.

Williams is now one of several women who have accused Uber drivers of sexual assault or harassment. One driver was arrested this week for allegedly kidnapping and raping a woman in Boston. A woman in New Delhi earlier this month was allegedly raped by an Uber driver.

The San Francisco-based ride-sharing service said Wednesday it plans to use biometrics, lie detectors, voice fingerprinting and other high-tech measures to vet potential drivers. “Putting safety first for each of the one million trips we are doing every day means setting strict safety standards, then working hard to improve them every day,” Phil Cardenas, head of global safety at Uber, said in a blog post Wednesday, adding that no background check or technology can fully prevent these incidents. “We owe it to all our riders, driver partners and communities around the world to examine what we can do better and then do everything we can to make more progress on safety.”

Uber has been in the hot seat since Buzzfeed reported that the Uber’s Executive Vice President of Business Emil Michael said the company should spend “a million dollars” to hire opposition researchers and journalists to dig up dirt on those who are critical of the company. Michael later apologized for the remarks.

Oregon officials filed a lawsuit against Uber last week to shut the ride-sharing service down in Portland, just days after it launched in defiance of city regulations. Uber agreed Thursday to suspend its operations in Portland for three months while city officials revise rules governing taxis and the use of ride-sharing apps, CNET reported.