Zachary Ruff, an assistant principle at Downingtown STEM Academy in Downingtown, Pa., is seen confronting two teenage anti-abortion protesters outside of the school on April 21. (Alliance Defending Freedom)

An assistant principal in Pennsylvania resigned Thursday after a heated argument last month with two teenage abortion protesters that was caught on video.

Zachary Ruff, of STEM Academy in Downingtown, Pa., was filmed confronting two abortion protesters April 21 in front of the school. One protester carried a sign with a graphic image of an aborted fetus.

“Sir, we’re actually exposing the holocaust that’s happening in America,” said Conner Haines, a home-schooled 16-year-old who was protesting at the school with his 19-year-old sister, Lauren Haines.

“There is no holocaust happening in America,” said Ruff, who has been with the Downingtown district for 13 years. “If you want to talk about a holocaust happening in America, go into an inner city, and talk to the poor and underprivileged.”

As the argument stretched for almost 20 minutes, Ruff said: “You and Trump can go to hell” and “Listen here, son: I’m as gay as the day is long and twice as sunny. I don’t give a f — what you think Jesus tells me.” At one point, he sang, “I Love a Parade” to silence the protesters.

After the Downingtown School District apologized for the incident and Ruff had an administrative hearing, Ruff resigned because it was “the best thing for his students,” according to a statement from the school district released Thursday.

“Dr. Ruff knew that the conduct he displayed was not representative of who he is and was not representative of the kind of educational leader he prided himself on being,” the statement said. “Dr. Ruff has acknowledged that the demonstrators had a right to be on a public sidewalk. He acknowledged that his conduct cannot be defended or condoned and he deeply regretted his actions as displayed on the video.”

Ruff didn’t return email and phone messages, and his attorney didn’t immediately respond to requests for comment.

The incident drew national attention that resulted in “hundreds” of messages to the school district, some supporting Ruff and some criticizing him, the statement said. The Alliance Defending Freedom, a Christian legal organization that represents the protesters, sent a letter to the school demanding they have the chance to address interested students at an after-school assembly.

“People of faith shouldn’t be discriminated against for expressing their beliefs,” ADF senior counsel Kevin Theriot said. “That’s exactly what happened here.”

Zach Ng, a 15-year-old sophomore at STEM Academy and the leader of a group of students who sought to save Ruff’s job, said students didn’t agree with his conduct but didn’t wish to see him dismissed.

“We don’t want to lose Dr. Ruff,” Ng said before the resignation was announced. “He’s a great principal, the heart and soul of our school.”