An assistant principal at the prestigious Downingtown STEM Academy has been placed on paid leave after being video-recorded cursing at two teenage anti-abortion protesters on school property, telling them that aborted fetuses were "cells," that he was gay and didn't "give a [expletive] about Jesus," and then loudly singing "I Love a Parade," apparently to drown out the pair.

On April 21, Zach Ruff, 40, dean of academics and student life, confronted the protesters while cars were leaving school at the end of the day. Connor and Lauren Haines, brother and sister, do not attend the academy and are thought to be from the Philadelphia area.  They held religious and antiabortion signs as students drove past.

On Thursday, as the video spread online and students learned what had happened, several started a petition asking the Downingtown Area School District not to fire Ruff, who has worked there 14 years. The petition, which now has more than 21,000 signatures -- the district has 12,000 students total -- said that Ruff was a "crucial and valuable" employee and that he has tried to make sure "that his students are safe and have a comfortable environment to learn in."

Watch the video (warning, it includes offensive language):

The district has strongly condemned his actions, issuing an apology on its website and saying it has launched an investigation.

"We are so dismayed, so dismayed," said Patricia McGlone, a spokesman for the district, the eighth largest in the state. "We don't condone or support" Ruff's actions. "We believe those students had a right to be out there on public sidewalks."

Superintendent Lawrence Mussoline said in a statement that he had hired Ruff as one of two assistant principals at the 787-student high school, twice named the top public school in the state.  He said that he has "a lot of respect for" Ruff, but that his "comportment" was "something that I would never have expected from this educational leader."

Mussoline said he had received passionate emails for and against Ruff, some suggesting that the incident did not merit suspension. "I disagree," the superintendent said, noting that the altercation had become national news. "We need to ensure that nothing like this happens again."

In the 10-minute video,  Ruff can be seen coming out of the school to tell the pair that they had to leave. The confrontation escalated when the two said they were on a public sidewalk and were allowed to be there. Ruff put himself between them and the line of cars, as if trying to block students from seeing the signs. He waved as they drove by.

Soon both sides were threatening to call the police.

The encounter got heated when the teens started talking about the "holocaust of abortion" and Ruff barked, "They're cells. ... You're at a science-based school." At one point he said, "You can go to hell, where they are, too,'" motioning toward the sign.

During the confrontation, he also snapped, "You and Trump can go to hell."

Later, Connor Haines said, "Sir, you need to turn to Jesus Christ."

"I'm as gay as the day is long, and twice as sunny," Ruff declared. "I don't give a [expletive] what Jesus tells me and what I should and should not be doing."

Ruff repeatedly told the teens they had no right to show the abortion pictures to his students, whom he called "innocent kids." He claimed Downingtown STEM had not had a pregnancy or abortion case in the last five years.

The school district said it did not know where the Haineses lived, or what school they attended.  Neither could be reached for comment. In an interview with a Christian news site, the Liberator, Connor Haines said he didn't expect such "hostility" at a school. "When [Ruff] was up in my face, my heart started beating crazy fast. But I wasn't really scared because I had my camera running, there were many people watching, and God has always protected me in the past," said Haines, who reportedly is 16.

During the dispute, an unidentified man entered the scene and defended the protesters, saying they were on public property. "He can do whatever the [expletive] he wants," the man said, just inches from Ruff's face. When Ruff threatened to call police, the man walked away, saying, "Another loony, wacko liberal."

As the Haineses started shouting out to students, Ruff turned to singing, and even appeared to dance a bit.

Ruff recently received his doctorate in educational leadership and management from Drexel University. Previously, he had been a social studies teacher and assistant principal at Downingtown High School East.

Zach Ng, 15, one of four students who started the petition, said students overwhelmingly supported Ruff, though they recognize his behavior was "inappropriate."

"He lost his temper," he said.

He called Ruff "the heart and soul" of the school. "His spirit is what makes the school a success. He's one of the most popular people there. There's unanimous love for that guy, no matter what," he said.

He said students plan to attend the next school board meeting, on May 10, to speak on Ruff's behalf and present their petition.

"We all support him," he said, "and want to see him back in his office next year."