Many startups have to learn to respond when things go horribly wrong with their products, but that lesson comes more quickly--and more frequently--for those that allow users to remain anonymous. 

Kik, a popular anonymous messaging app, is in the news following reports that Nicole Lovell, a 13-year-old Virginia teen found dead Saturday, may have met her alleged murderer on the app. As a result, some child-safety advocates are voicing their concerns about the app. 

"I'm willing to say Kik is the devil for young children," Pamela Casey, a district attorney in Blount County, Tennessee, told Good Morning America Wednesday morning. 

"It really becomes a private hunting preserve for some of these pedophiles," Callahan Walsh, a national outreach and marketing coordinator for the National Center for Missing and Exploited Children, told GMA.

Kik told Inc. that it cooperated with the FBI during the Lovell investigation. "This is a terrible tragedy, and our hearts go out to Nicole and her family," a spokesman said. 

Parents and child-safety groups are concerned in particular about users' ability to search for other users to send texts to based on age, location, and school, among other factors. And Kik doesn't display users' full names. 

Kik said that the app had features to block users and report inappropriate content. The company also formed a partnership in March with anti-child abuse organization Virtual Global Taskforce (VGT) and Microsoft PhotoDNA Cloud Service, to detect and eliminate "exploitive images."

Kik's website also includes a page for law enforcement officials, which tells them what to do if they suspect someone who used the app has committed a crime.

Despite the safety concerns, anonymous messaging apps continue to be popular among teenagers. The Waterloo, Canada-based Kik, founded in 2009, has 275 million users, and its website claims that more than 40 percent of U.S. teens use Kik. 

Yik Yak, an app that lets users post anonymous comments that other Yik Yak users within a 1.5 to 10 mile radius can see, has also struggled with user issues. Some college and high-school students have used the app to bully other students, or make violent threats against the school. Like Kik, Yik Yak has a page for law enforcement officials.

In 2014, Yik Yak co-founders Brooks Buffington and Tyler Droll banned high schoolers from using Yik Yak. They told Wired that Yik Yak drew virtual barriers, called geofences, around schools.

"We realized that if we wanted to create something that's long term and sustainable, the communities we're developing need to be constructive ones," Buffington told Wired. Yik Yak didn't respond to's email request for comment.

Venture capitalists aren't any less interested in investing in anonymous messaging, which, with their millions of users, have the potential to generate big revenue. Kik is valued at more than $1 billion, while Yik Yak is valued at about $400 million.