"USC is a great school, but this should not have happened," she said. "This incident has resulted in my being less trusting of doctors altogether. I trusted USC as an institution, but USC has let me down."

Allred said she had heard from other women complaining about Tyndall, and she released statements from two of them relating similar claims.

The university has acknowledged that Tyndall was the subject of eight complaints dating to 2000. It confirmed last week that it paid him an undisclosed amount last year to leave campus.

The university said that it began termination proceedings in 2017 but that Tyndall threatened to sue, alleging retaliation and age and gender discrimination. It said it agreed to the payment "rather than engage in protracted litigation."

The university also created a hotline to which former patients could report complaints. A spokesperson for the university said Tuesday that the hotline had received about 300 calls so far.

"It's appalling, it's troubling and it goes against what I stand for as a physician and as a college health leader," Dr. Sarah Van Orman, the university's associate vice provost for student affairs and chief health officer of the student health service, told NBC News.

"It's shaken both the folks here on campus, me personally, our staff at the health services and people nationally," said Van Orman, who was appointed to the position after Tyndall left.

Manly, who represents four of the women who have sued the university, said Monday that the scandal, which was ignited by an investigation by The Los Angeles Times, had exposed only the tip of the iceberg.

"He'd been doing this for 30 years, so the numbers could be staggering," he said, adding that many of Tyndall's patients had little experience with gynecologists and didn't know that what he is alleged to have been doing was inappropriate.

The Engemann Student Health Center on the campus of the University of Southern California in Los Angeles. Robyn Beck / AFP — Getty Images

The letter from the professors noted that in one of his first statements on the case, Nikias referred to Tyndall's alleged behavior as a "breach of trust," but it said, "President Nikias' own actions and omissions amount to a breach of trust."

"He has lost the moral authority to lead the university, and in addition, to lead the investigation of institutional failures that allowed this misconduct to persist over several decades," they wrote.

Separately, more than 2,300 students had signed an online petition by Tuesday also calling for Nikias to quit, alleging that "under his leadership, cover-ups have spoiled the USC reputation and have hindered real change on campus to keep students safe."

Nikias, who holds faculty appointments in electrical engineering and the classics, has been president since 2010.

In a 20-page "action plan" that he distributed Tuesday to address the scandal, he said he was "truly sorry these events happened within our community" and felt deep regret for "how much distress they have caused."

Nikias announced the appointment of a President's Campus Culture Commission to monitor the action plan, which envisions rewriting the university's ethics code, developing "coherent and centralized systems" for handling complaints and ensuring protection "when possible" for anyone who steps forward with a complaint.