Transcript for First responders use drones to aid hurricane rescues, emergency response
Reporter: A bird's eye view of the devastation of the British Virgin Islands today. The scope of hurricane Irma's destruction captured by a drone. And in the wake of hurricane Harvey in Texas more aerial images showing structural damage prompting an evacuation. The roof was caving in. And there were people in there working. Reporter: These aircraft deployable in just minutes are used by more than 300 state and local agencies across the country. Now going beyond just looking down. Drones are also saving lives. From flying a safety line for this swift water rescue of two stranded boys in Maine to south Carolina, where a drone's thermal imaging found stranded kayakers in the dark. In the lone star state the public safety U.A.S. Response team was one of the first groups to dispatch drones in emergency situations. If you get five or six of these things in the air, there's pretty much nothing that we can't cover with these things from the air. This man and this woman are in this home that is totally surrounded by water. Reporter: They are the team on he scene of this flash flood. It's just -- it's crazy. Constant water. Reporter: That's William and Tracy Castel stranded back in 2015. All I could see was water. And it wasn't just standing water. It was flowing water. The feeling of helplessness was overwhelming. Reporter: With the danger swelling by the minute pilot Garrett brill attached a safety line to his drone. We were able to precisely deliver it right to his hand. We've seen a brilliant use of a drone here. I pulled that heavier rope across the water and secured it to the porch, and the porch beams, and they were able to use that to use the rescue raft to try to get out here. Reporter: A helicopter eventually got the kastels to safety. But thdt first drone offered a look at how this high-flying technology could be a lifeline. Everybody realizes that these are more than just eyes in the sky. This is a multipurpose tool that every department needs to have. Reporter: ABC attended one of the response team's training exercises. Let's go. Reporter: Simulating an active shooter scenario. Volunteers playing frightened school kids and teachers. Mannequins on the ground representing the wounded. And the Mansfield police department in north Texas, their weapons, paintballs. Taking down the bad guy in a matter of moments. They got him. Reporter: Let's watch again. This time with our cameras fixed on that aircraft. The first eyes inside. Speeding down the hallway. Officers following close behind. The hallway's clear. Reporter: The drone's pilot relaying what the drone sees to his team inside. Suspect left. Suspect left. Reporter: Then the takedown. The entire time that drone was watching what he was doing. That's how they knew where to go. The man behind the sticks, Barry Moore. Before the drone goes through those doors, what's going through your mind? Keep the officers out of coming inside. Make sure I can keep eyes on the bad guy and make sure they're not walking into something that's going to get them killed. Reporter: For firefighters the drone brings a clearer picture than the naked eye. We are suiting up because we're actually going to go in there and show you what the drone can do to help save people in a fire. Let's go. We're dog going in, guys. We're going in. Reporter: With members of the Joshua fire department I'm led into a smoke-filled building. I see the fire but I can barely see anything else. Reporter: I crouch in the corner, playing a trapped victim. Even from the outside the smoke is blinding. No way for rescuers to know if anyone's inside. But a quick view of that thermal camera, and there I am. All right. We are out. Reporter: You can see the thermal camera is what saw what was happening inside. And really for any firefighter at's what's going to make the difference. They're going to be able to see who's in there, who's walking around. How often are you using this technology? We're using it every fire we have. Every fire. Every fire we have. Reporter: High-tech firefighting. That's the way to do it. These first responders also go high-tech for search and rescue. Recently in Colorado a drone spotted these two lost hikers and their dog in just two hours. The perspective that it give differ gives you from the air is completely different from a searcher on the ground. When a searcher walks through woods like this all they see is thick woods. When you get up above you realize there's a lot of patches, a lot of holes. You can see all the tells. Reporter: As night falls I head into cleburne state park. It's up to the first responders to fall me. So now it's getting really dark. We're running out of light here. And hopefully they're going to get that drone to me soon. Within minutes the drone appears, carrying a raid Crowe and glow sticks so I can see their special delivery. I see the drone right there. Make sure he sees me. I see the glowstick. He's going to drop this. But he's got to get close. Let's see if he can see me. He's got it. I have the walkie-talkie. I'm not hurt. But I'm a little lost back here. It's dark. We will send a search team in for you right now. Reporter: Finally, a drone with a spotlight appears, guiding that search team. They have a spotlight on a drone. This is the kind of spotlight you might expect from a helicopter. Wave to the camera and say hi. You found us! I can't believe it. Reporter: A light in the dark for me. And as hurricane Irma looms, drones may be called to action yet again in Florida. For "Nightline" I'm gio Benitez in cleburne, Texas.
This transcript has been automatically generated and may not be 100% accurate.