Almost everyone knows each other in Camp Hill, Pa., a cozy little community of about 7,500 people near Harrisburg.

But like many places across the country, Camp Hill is on lockdown because of the coronavirus pandemic. So last week, Leigh Twiford, president of the local borough council, held an online town hall using a Zoom video conference.

"We just wanted to get the word out to our residents that ... we're here, we're open, you know, the doors are locked, but we're still working," Twiford said.

"Here are phone numbers that you can call if you need help. If you're looking to volunteer, here's how you can do that. It was kind of just a way to communicate with our borough, because we haven't been able to."

Things quickly went off the rails.

"I looked up at my screen from the report I was reading and there was porn on the screen," she said.

Camp Hill had just been "Zoombombed." These attacks, in which hackers scrawl offensive comments, or post pornographic or racist images, have become more frequent on video conference calls.

When Twiford tried to kick the intruders out, they kept coming back.

"They would figure out legitimate names of people that were really residents of our town, and so they'd signed back in under that name," she said. "So I didn't know who was a real person and who wasn't a real person."

Twiford had planned to take questions at the end of the town hall. Instead, she shut it down.

Her experience is not unique. Zoom says it had 200 million daily users in March. It has become really popular because it is so easy to use. School classes, AA meetings and religious gatherings have moved onto Zoom — and so have harassers.

That is creating a particular problem for public officials, who are trying to keep important services running and their citizens informed during this crisis.

"I just can't tell you how frustrating it's been to try to talk to people about how they apply for unemployment benefits or small-business assistance, and have all of this other extraneous stuff going on," said Connecticut Lt. Gov. Susan Bysiewicz.

Several virtual town halls she has held in recent days were hijacked with what she described as an "avalanche" of racist, sexist and homophobic comments.

Zoom says it condemns such attacks. It has changed default settings, so people need a password to join a meeting, and new participants are kept in a virtual waiting room until the host lets them in. Hosts can also turn off screen-sharing to block participants from posting inappropriate content.

But those who need to hold public meetings are struggling to figure out how to let people participate without becoming targets for harassment.

Sunshine laws like Michigan's Open Meetings Act require local governments to make meetings public and open for comment.

"We honor every piece of that Open Meetings Act," said Kalamazoo Mayor David Anderson. "We do not get together without announcing it in advance and discuss[ing] how we're going to vote on things. That is meant to be done in the light of day."

Offline public forums can also be disrupted, of course. But Anderson says there's more accountability when people have to stand up and give their names. He said he is concerned about any online platform where people can be anonymous.

After a Kalamazoo city commission meeting was Zoombombed in March, Anderson began working with the city attorney to figure out how to hold public meetings while keeping online trolls away. But, Anderson says, they also need legal guidance from the state government.

"Can we, for example, collect recorded messages in advance and then see whether they're appropriate to play or not? Does it really have to be live in real time?" he said.

He hopes to have an answer before Kalamazoo's next public meeting later this month.

Editor's note:Zoom is among NPR's sponsors.

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