BOSTON — Katherine Clark walked out of her Melrose house at about 10 p.m. on day last February to find police swarming her lawn in response to what they described as a "computer-generated phone call" of shots fired.

The congresswoman quickly realized it was a case of "swatting" — the sending of hoax emergency reports designed to provoke a response by police SWAT teams.

"There was that moment of panic," Clark said. "I can only imagine if you've never heard of this ... how absolutely terrifying it would be."

The Massachusetts Democrat was not only familiar with the practice — which often targets celebrities, domestic violence survivors and public figures — she was pushing a bill to outlaw the practice.

Since taking office in 2014, the state's newest member of Congress has carved out a niche as a prominent critic of online harassment.

Clark said she hadn't envisioned that role when she ran to fill U.S. Sen. Edward Markey's old House seat after Markey was elected to John Kerry's Senate seat two years ago.

That changed shortly after taking office when Clark heard the story of Brianna Wu, a software engineer and game developer who found herself the target of online harassers. The abuse grew so frightening — with threats of rape, death and castration — that Wu left her home.

The case helped spotlight an online campaign during which women were harassed for criticizing the lack of diversity in the video-game industry.

Wu was also a constituent. That led Clark to press the House to adopt language calling on the Department of Justice and the FBI to make online abuse a priority. Clark went on to file a bill to give grants to states to help local law enforcement develop those training programs to investigate online abuse.

"People were choosing to leave professions and not be online when they needed to be," said Clark, who soon found other areas of concern.

Clark urged internet database officials to protect privacy of targets of abuse from "doxing" — the online release of a person's home address — and pushed a bill that make it a crime to use of the interstate telecommunications system to knowingly transmit false information with the intent to cause an emergency law enforcement response — an anti-swatting bill.

Earlier this year, Clark also criticized the popular online annotation service Genius for not doing enough to block malicious users from injecting their comments directly into protected content. The company responded by announcing it was adding a button to allow anyone to report abuse on any annotation.

Ari Ezra Waldman, a professor at New York Law School specializing in privacy and online harassment, said online abuse results in real harm. He said a common piece of advice to victims — to turn off their computers or stop using Facebook or Twitter — is misguided.

"It blames the victim. It absolves the aggressor," he said. "Also it's incredibly difficult for someone to detach from an online world in 2016."

Clark said her next target is sextortion — the practice of using naked or topless images of young women or teens to pressure them into offering more pictures with the threat of posting the original images online.

"We're seeing a real spike in this sort of very dangerous, depraved practice," said Clark, who hopes to file a bill this week to create a federal crime of sextortion.

Clark said the wider problem is a lack of diversity in Silicon Valley and high tech companies that can drown out the voices of women, minorities and members of the lesbian, gay, bisexual and transgender community.

"If you do not have women and people of color at the table, you are probably not going to come up with a product that can be enhanced and anticipate the end user's experience as well as you could," she said.