Several images circulating on Twitter that purport to show people missing after the attack in Manchester last night have turned out to be a hoax, The Washington Post reports.

Following an explosion at an Ariana Grande concert in Manchester on Monday, images of missing teenagers who had attended the show began to appear on social media. Many of the images have gone viral, as people eagerly retweeted them in an effort to help. But several of the people in these photos are YouTubers, journalists, and internet personalities who were never actually missing.

One particular photo collage, which was reportedly shown during this morning’s episode of Fox & Friends, features several images of YouTube celebs. As the YouTuber Keemstar pointed out on Twitter, one of the images is a screencap of a video by ProSyndicate, a vlogger based in Manchester who was not at the concert.

That same collage features the YouTuber EvaDeMetal, who, perhaps unwisely, started the hashtag #PrayForEva, after it was falsely reported that she was missing. It also features an image of the man behind Report of the Week, a popular fast-food review show on YouTube. Last night, he posted a video on YouTube in response to the claims he was missing called “I am alive.”

“This unfortunately was just an effort done by various trolls, and certain website users just to try to mislead the general public with fake news and just to try to get some laughs out of it,” he says. He noted that he was safe in the US at the time of the attack.

Several other images purportedly showing missing people have been called out as fake, including a few journalists and an image of 4chan founder Christopher Poole, according to BuzzFeed.

As The Washington Post points out, internet hoaxes like these often follow major tragedies. The originators of these tweets might post them as a joke or as a way to get retweets, but they prey on sympathetic Twitter users who will share them without thinking twice. Tweets like Keemstar’s that attempt to debunk the originals have not been shared as widely as many of the fake images.