(CNN) -- A menacing tornado churned behind Mike Eilts as the storm chaser's truck sped away.
It seemed like the perfect escape, until Eilts realized he was barreling toward a dead end.
The team from the National Severe Storms Laboratory had two choices: one bad, and the other worse.
"The decision was either to get out of the car and jump in the farmer's yard," he says, "or to try and beat it."
Driving toward the tornado was the only way out.
The truck shook as the edge of the tornado pushed it, Eilts recalls. But he floored it and somehow made it to safety.
That was more than two decades ago. But even now, the sight of the dirt swirling and the sound of screams that day are memories that remain fresh in Eilts' mind.
It was a close call -- the kind of thing Eilts says you don't forget.
The deaths of three storm chasers in Oklahoma have sparked a surge of questions about people who drive toward tornadoes when others run away.
Who chases storms? Why do they do it? And what makes it worth the risk?
Visiting the 'tornado zoo'
Some say storm chasing provides valuable scientific information that helps increase warning times for people in harm's way. Some argue it's a dangerous hobby for thousands of inexperienced onlookers searching for a thrill. But others stress that there are safe ways to chase tornadoes, a kind of tourism that one company compares to a cruise vacation.
Eilts, who once worked as a government researcher and now is the president and CEO of Oklahoma-based Weather Decision Technologies, says he's seen both sides.
It used to be that the only people going toward tornadoes were trained scientists, he says.
Now, when he's observing storms, a different sort of sight makes Eilts turn around and head home.
Not the ominous funnel clouds.
These days, Eilts says what he fears are car after car, parallel parked on highway shoulders, with droves of people stretching their arms into the air, trying to capture the "money shot."
"I call it 'tornado zoo.' They think they can just drive up like it's a lion on the other side of the cage," he says. "They take a picture or video of it, not thinking that the whole thing can expand in literally seconds, a new suction spot can come out, and you have no time to react to that kind of thing."
Martin Lisius, who's been chasing storms since 1987, calls them the "children of 'Twister.'"
The 1996 film, he says, spawned a generation of storm chasers who search for thrills with no idea of the risks.
"They're acting like they're in a movie," he says.
Some of them seem to be motivated by fame or fortune, he says, or maybe even the hope that their video can land on television.
For years CNN and other national television news networks have purchased tornado videos shot by freelance storm chasers. Traditionally the fees are in the hundreds of dollars, but could be more than $1,000 for editorially important images.
Eilts says he worries that one of these days, a storm will strike while thousands of people are stuck in traffic jams caused by storm gawkers. Already, he says, professionals have a harder time collecting data, and emergency responders struggle to reach areas that are in danger.
"I think it causes a lot of problems for scientists that are trying to do their jobs, for scientists that are trying to get sensors in the right place," he says. "Now they're worried about, 'How do you stay out of the parking lot of storm chasers and stay safe?'"
Studying the science of storms
The National Oceanic and Atmospheric Administration says that storm chasers have given valuable research to the government.
And many storm chasers say there's serious science behind their efforts.
Probes and sensors placed directly in a tornado's path, they say, detect things research can't reveal from afar.
"It's very hard to understand what's really going on in that small area near the ground of a tornado," Eilts says.
But observing details like wind, temperature, pressure and humidity in that area, he says, help scientists understand how and why tornadoes form, and developing warning systems that are more accurate and give people more time to take cover.
"You can't measure it with radar. You can see things aloft. You can't measure what's on the ground. And so (these are) very dedicated people that have risked their lives to do that," he said. "There's value created by that. We understand. We'll be able to model tornadoes better."
When storm research started out, forecasters had no lead time to warn people that tornadoes were approaching. Now, the average lead time is 14 minutes, Eilts says. Someday, with the help of scientific research from storm chasers and others, he says, warnings might be more precise and people could have up to an hour to take cover.
When Lisius was a kid, he won a prize for a science fair project on thunderstorms and snapped photos of lightning from the kitchen window of his family's north Texas home. Now he runs Tempest Tours, a company that offers storm-chasing expeditions for tourists -- and a chance to photograph storms from a much closer vantage point.
"It's like a cruise, you know," he says. "We have a schedule. We have a departure and return. We have a port city, which we call our base city."
These port cities don't have ocean views. Arlington, Texas; Oklahoma City, Oklahoma; Denver, Colorado; and Phoenix, Arizona are among the spots where Tempest Tours take off.
"There's a fishing season and a hunting season. And the best time to see tornadoes for us is in the spring," he says. "And the best places to see them are those places."
Some chasers in the niche tourism industry that has sprung up around storms take risks. But not Tempest Tours, Lisius says.
"It's all about education and teaching them about the atmosphere," he says. "It's not a thrill seeking tour. That's not us."
When the storm struck El Reno, Oklahoma, last Friday, Lisius said he was leading a tour about a mile away, observing from the field with more than a dozen people.
The storm formed rapidly, and turned quickly toward the southeast -- both unusual signs, he says, that showed it was time to take cover.
"We left. It was not a close call because we took quick action to avoid a close call," he says. "It's what we do on a regular basis."
But for a tour group watching from afar, he says, it's easier to change course than it is for researchers who are up close, measuring details about tornadoes.
"Our mission is to teach people about severe weather, and we can get close enough to a tornado to see it and take good pictures of it, but certainly we don't have to get in the path," he says.
From science to 'soul searching'
Nobody knows exactly how storm chasers Tim Samaras, his son Paul Samaras and Carl Young died in a storm that struck the Oklahoma City area on Friday. Friends and family describe them as dedicated scientific researchers known for putting safety first.
The National Oceanic and Atmospheric Administration says it appears to be the first time researchers intercepting a storm's path have been killed.
Lisius and many other longtime storm chasers say they're devastated and shaken by the deaths of colleagues with such extensive experience and training.
"This is the first time this has happened," said Tyler Constantini, who has been chasing storms since 1998, "and I'm sure we'll learn a lot from it and, hopefully, do a little soul searching, try to figure out what we need to do to try to stay safer out there."
The deaths should give everyone pause, Eilts says, and experts should weigh whether new guidelines are necessary to keep storm chasers safe.
But Eilts says there's no doubt that studying tornadoes on the ground is crucial.
"Our whole country's built upon research and development and enhancement. Ultimately if we can save 100 lives more every year because we have better tornado warnings, that's worth it," he says. "Being in the field is an important part of that research. That has to go on."
CNN's Thom Patterson, Dave Hennen, Sean Morris and Brandon Miller and contributed to this report.