Uber Technologies Inc. Chief Executive Travis Kalanick called for an investigation Sunday into allegations of sexual harassment, bias and mismanagement at the company after a former employee wrote a scathing blog post about her experiences there.

Susan Fowler, who said she started working at Uber in late 2015 as a site reliability engineer, claimed her male supervisor made sexual advances toward her via company chat on her first day on his team. “It was so clearly out of line that I immediately took screenshots of these chat messages and reported him to HR,” she said, but was told he would not be punished because he was a “high performer” and that was the first complaint against him.

She said she was given two options: Leave his team, for which she was highly qualified, or stay and likely get bad performance reviews from him. “One HR rep even explicitly told me that it wouldn’t be retaliation if I received a negative review later because I had been ‘given an option,’” Fowler wrote.

Fowler left his team, but said she later discovered other female employees had also reported inappropriate interactions with him. “It became obvious that both HR and management had been lying about this being ‘his first offense,’ and it certainly wasn’t his last,” she wrote, claiming that HR refused to take action against him. The male supervisor eventually “left” the company, Fowler said.

She detailed “a Game-of-Thrones political war” among management, involving managers undermining their bosses in order to take their jobs. “One of the directors boasted to our team that he had withheld business-critical information from one of the executives so that he could curry favor with one of the other executives (and, he told us with a smile on his face, it worked!),” Fowler wrote.

Fowler also described an opaque and unfair performance review process and a continued pattern of sexist behavior within the company, including one complaint about how female workers were denied free company leather jackets that male employees got “because there were not enough women in the organization to justify placing an order.” After making numerous complaints and still receiving no support from human resources, she said she was told “it was unprofessional to report things via email to HR.”

Fowler left Uber after a year, noting that other women fled the company during that time. “When I joined Uber, the organization I was part of was over 25% women. By the time I was trying to transfer to another eng organization, this number had dropped down to less than 6%,” she said.

In a statement late Sunday, Kalanick called the charges “abhorrent” and said the company would launch “an urgent investigation into these allegations.”

“I have just read Susan Fowler’s blog,” Kalanick said in a statement. “What she describes is abhorrent and against everything Uber stands for and believes in. It’s the first time this has come to my attention so I have instructed Liane Hornsey our new Chief Human Resources Officer to conduct an urgent investigation into these allegations. We seek to make Uber a just workplace and there can be absolutely no place for this kind of behavior at Uber — and anyone who behaves this way or thinks this is OK will be fired.”

Uber is no stranger to controversy, and its top executives have come under fire for sexist comments in the past. For example, Kalanick was criticized for making a crack about “women on demand” — “Yeah, we call that boob-er” — to GQ in 2014, and senior vice president Emil Michael threatened in 2014 to launch a smear campaign against a female journalist.

Silicon Valley’s male-dominated “bro” culture has been the subject of much debate in recent years, but efforts to improve diversity have been slow. A survey in 2016 found 60% of women in Silicon Valley tech companies had been subject to sexual harassment.