“Gunshots in my area. Currently freaking tf out. I’m not getting sleep tonight. 🤦‍♀️“

“Bro I literally live 5 minutes away from this, hearing this is making me shake 🥶.“

Police radio scanner apps have exploded in popularity since protests erupted across America over the death of George Floyd, a black man who died in Minneapolis police custody last week. The apps allow volunteers with special radio equipment to broadcast first-responder communications to thousands of listeners online.

The comments above were from an online message board associated with one such app, 5-0 Radio Police Scanner, which soared to the top of the iPhone download rankings over the weekend. Costing $5, the app became the most downloaded in the “top paid apps” category in Apple’s App Store.

Another version of the 5-0 app that’s free vaulted over TikTok, Twitter, YouTube, Facebook, and Instagram—no small feat—to place third in “top free apps” in the App Store. However, the app could not touch Zynn, effectively a TikTok clone, and Zoom, the unshakeable videoconferencing app, which maintained the Nos. 1 and 2 spots on the “free app” leaderboard, respectively.

Interest in rival police radio scanner apps has been surging amid the current strife. Among the top 10 “free” apps on Monday were rivals Citizen (No. 5) and Police Scanner Radio & Fire (No. 7), while Broadcastify Pro ($3, No. 13) and Police Scanner + Pro Edition ($5, No. 17) were among the “top paid.”

Protesters and bystanders alike are flocking to the eavesdropping apps as people seek to keep tabs on flare-ups of civil unrest. The apps offer raw, real-time information about incidents involving looting, fires, shootings, as well as the deployment of law enforcement officers.

Some government officials and law enforcement oppose the apps. Fearing that smartphones have made it too easy for criminals and others to track their pursuers, some police departments are moving to encrypt their radio communications to prevent eavesdropping.

Tuning in to the free version of the 5-0 app on Monday, Fortune listened to crackle-voiced reports of missing persons, the whereabouts of suspects, and descriptions of vehicles followed by police officers in various U.S. cities, including Los Angeles, Chicago, and Davenport, Iowa. The snippets of conversation represent reports from in the field, including some unverified claims and misleading information.

While the protests and state countermeasures have provoked angst, disruption, and violence nationwide, the situation has created a lucrative opportunity for the entrepreneurs behind these apps.

In a statement to Vice Motherboard, which first noted the surge in popularity of police scanner apps, Allen Wong, the 5-0 app’s developer, described the rush of interest as “the largest spike overall” since the app’s debut more than 10 years ago. For four days running, “the numbers of users have almost doubled the previous day,” Wong added, noting that “almost half a million active users” had tuned in on Sunday.

Protests and conflict continued to unfold on Monday. As one 5-0 app user put it to another user worried about an onrush of police sirens: “Don’t stress out. Just breathe and it will be ok. Stay safe.”