GEOFF BENNETT: Ever since the deadly wildfires began in Los Angeles two weeks ago, residents have largely turned to one app for the most up-to-date information.

It's called Watch Duty.

And Stephanie Sy spoke to two members of the small team who make it possible to make it possible.

STEPHANIE SY: Smoke filled the sky above Sekhar Padmanabhan's Los Angeles home on January 8, winds gusting around him.

Just a day earlier, the Palisades Fire began its deadly march across the Santa Monica mountains.

As a staff reporter for Watch Duty, Padmanabhan had a job to do.

SEKHAR PADMANABHAN, Staff Reporter, Watch Duty: We noticed it and saw it start and we saw it kind of take off, and then we assigned more people because it got bigger and bigger and bigger.

STEPHANIE SY: Watch Duty provides real-time updates and notifications from official sources during wildfires.

The free app has interactive maps allowing users to track evacuation zones, shelter locations, live camera feeds and fire perimeters, as well as information about containment on specific fires.

The core team is small, about 15 paid staff.

The operation also relies on some 200 volunteers.

SEKHAR PADMANABHAN: It was really tough.

We have people sleeping in shifts.

We had people who are up for 24 hours or more.

All of our work is designed to give people as much time as they can -- as we can to give them an informed ability to make decisions.

STEPHANIE SY: During the Palisades and Eaton fires, the app was indispensable, not just for residents, including celebrities like Jimmy Kimmel... JIMMY KIMMEL, Host, "Jimmy Kimmel Live": I downloaded that Watch Duty app.

STEPHANIE SY: ... but also officials.

Watch Duty's map was projected on a wall in Los Angeles' Emergency Operations Center earlier this month.

Shortly after the fires exploded, another blaze threatened homes near Hollywood, not far from where Padmanabhan lives.

SEKHAR PADMANABHAN: That had an evacuation words basically just down the street.

And the helicopters were going above my house and I could hear with the window.

And I was watching it on Watch Duty.

And it was really, it was a surreal experience, because, like, I report on these things, but then it's my place, that, like, OK, where are my cats?

You know, what am I going to do with this?

So it was a real interesting perspective, but also peace of mind, because I knew that we had a number of people reporting on it and that would get the information that I needed, my sister needed, everybody else needed.

STEPHANIE SY: So this is an app you would trust with your own life?

SEKHAR PADMANABHAN: Yes, absolutely.

STEPHANIE SY: At the end of 2024, Watch Duty had nearly three million app users.

Since the Los Angeles area fires broke out, that number has almost doubled.

Software engineer and entrepreneur John Mills co-founded the app in 2021.

JOHN MILLS, Co-Founder, Watch Duty: The sad part is, is, we were ready for this, right?

We didn't know it was going to be so bad.

But I'm glad that we were here and practiced in this.

It's been years and years in the making.

If you look back in time before Watch Duty existed, when I went through my first fire in 2020, the Walbridge Fire, you end up having 15 browser tabs open, and you're trying to piece all this together.

So, the insight was that this needed to be consolidated in one place.

STEPHANIE SY: Shouldn't the government have an app that is dependable and trustworthy and one which fire evacuees can readily reference for reliable information on evacuation and active fire areas?

JOHN MILLS: I mean, sure, that'd be great.

It'd also be great to have more engines, better pay, more water, more infrastructure, better forest management.

So I absolutely think they can do better.

Again, it's just not what the government does very well.

Like, no one talks about any great government Web site.

And I wish that would change.

STEPHANIE SY: We were in Los Angeles County when a massive alert went out to all 10 million residents of Los Angeles County.

That ended up being kind of a false alarm for most people.

But your app did not send out that evacuation alert, from what I understand.

Is that part of human vetting?

JOHN MILLS: Yes, that's correct.

I mean, we don't just let machines or systems blanket send information out blindly.

And when that went out, we saw a lot of the systems around us crashing, whether it was the evacuation software, the L.A. County Web site.

They all went down.

And so everybody came to us.

We were doing about three million users a minute, about 100,000 requests a second.

And so our systems were getting pegged and we were able to stay afloat.

STEPHANIE SY: The organization currently covers fires in 22 states, but it has plans to expand with coverage of other natural disasters like hurricanes.

JOHN MILLS: We're just trying to take our time to understand those environments, right?

We don't have a move fast and break things mentality.

We just need to deliver every day consistently and continue to keep the trust of our community.

STEPHANIE SY: Watch Duty is a nonprofit funded through donations and memberships for premium tools such as tracking air tankers.

But Mills says, for users who simply need lifesaving information from a single source, the app will always be free.

For the "PBS News Hour," I'm Stephanie Sy.