This walkie talkie app got six million new users in one week as Florida prepared for Hurricane Irma

“Is it safe to go to any Miami-Dade hospitals? It’s an emergency.”

“Are there tornadoes in Miami?”

“Where is the eye of the storm?”

These are just some of the more pertinent questions that people are fielding on the walkie-talkie app Zello. The app, which was founded in 2012, is serving as the de facto source of real-time updates, as well as access to emergency information, as Hurricane Irma makes landfall in Florida.

Listening in on the channel for 10 minutes on Sunday provided pertinent updates and guidelines such as:

“If you’re still looking for shelter text the word shelter and your zip code to 43362.”

“Please take the password off your cellphone so your kids can use it in the case of an emergency.”

“There is a tornado warning issues for West Lake, Osceola County.”

The app, which enables people to communicate on public channels on the app using Wi-Fi or cellular data, has seen one million new users a day since last Monday, according to Zello CEO Bill Morris. Zello is currently the top free app in the U.S. Apple app store and has more than 100 million registered users to date.

In addition to allowing people to field audio questions, the app also allows participants to upload screenshots with updates or pertinent information such as numbers to call if someone runs out of gas on the road.

“We’ve seen an explosion in a crisis before so that’s not so surprising,” Morris told Recode. “The main group in Harvey is called the Cajun Navy. They used Zello in prior years and they had great success a year ago during what was then the biggest flood since Katrina. So when they came to Houston they strongly urged the community to use Zello and one of the reasons is because Zello works when most other things don’t.”

As people start losing their power all over the state, the channel is serving as an important source of information that Florida residents may have typically received in the past by watching local TV reports.

According to Morris, Zello has also seen surges in popularity during political and social conflicts in Egypt and Venezuela.

“Zello was adopted as the communication tool [in these situations] because voice is trustworthy in a way that text is not,” Morris said. “It’s much more intimate. Live voice demands attention from both sides. It’s a great way to communicate and coordinate with a group of people at once.”

While channel admins are providing real-time updates on wind speeds and which Florida counties have lost power or are experience flooding, they also spend a good deal of time attempting to moderate the channel and keeping it clear of spam and non-emergency questions.

“If you use profanity you will be blocked and when you need help you won’t be able to get it,” one admin repeatedly advised on the app.

“The core problem with public radio is you have bad actors,” Morris told Recode. “It’s very difficult with live voice. So we have over the years developed administration moderation tools and one of them is a trusted channel where you can only speak if you’re approved.”

This was also a problem dispatchers faced during Hurricane Harvey that recently slammed into Texas, Morris learned after having round table discussions with some of them in the days after the hurricane.

“They would bring up the problems, another one was other channels [that were] trending would come wreak havoc on these emergency channels and say ‘we want to cause problems because you’re beating us in trending,’” Morris said.

The app itself is free and Zello makes money off of its commercial offering called ZelloWork, for which the company has about 1,000 business costumers. Think of it as a dispatch or communication service for companies with employees who don’t typically sit at their desks — such as transportation companies.

This article originally appeared on Recode.net.