A flock of speed skaters flashed across a parking lot past children learning to roller skate and hundreds of other people who had gathered to skate or just to watch the action on a recent Sunday in downtown Nairobi.

A craze for roller skating has hit Kenya, fueled by its growing middle class and a love for speed.

Lameck Wafula has seen this phenomenon up close. For 27 years, he has taught choir in the sunken parking lot that covers a whole city block on Aga Khan Walk, using the spot because he didn't have to pay rent and he enjoys the open air.

A decade ago, he noticed that a few skaters began appearing on the lot. Then the sport really took off in 2010 when Nairobi County, which owns the lot, allowed skaters to use it on Sundays and holidays, providing a safer alternative to the streets.

Wafula's daughter became a skater, and he also got involved.

Today, he's the secretary-general of the Kenyan Federation of Roller Skating, which was created in 1997 with four members and now oversees 60 skating clubs. More than 100 schools feature roller skating at gym. A speed-skating tournament in June drew more than 400 participants from all over Kenya with hundreds more watching. A music video by Kenyan hip hop artist Octopizzo features skating. Even the police department sponsors a skating team.

As Kenya's middle class has grown, providing more income and leisure opportunities, so has its participation in skating and other sports like golf, according to Daniel Ngari, director of Kenya's Social Services Department.

The African Development Bank estimates that Africa's middle class rose to 313 million people in 2010 from 151 million in 1990. In Kenya, more people can afford cars, with the number of registered vehicles doubling from 2001 to 2009. Kenyan youth now spend $616 million annually on entertainment and outings. And that includes roller skating.

"This sport has grown so fast," George Obulinji, chairman of the Nairobi branch of the skating federation, exclaimed as he visited the parking lot on a recent Sunday. "We couldn't have expected it."

A group of skaters whooshed past him and rounded a corner, their arms swaying, their skates clicking on the tarmac. They glided past some jacaranda trees and picked up speed on a straightway. Tall buildings loomed overhead.

In each corner of the parking lot, entrepreneurs rent skates and give lessons. Entry-level in-line skates can cost $76 new, while renting skates is less than $3 for an hour.

Anthony Karanja began with rentals before buying his own and training for competition. After just one year, he is now the second-ranked speed skater in Kenya.

He and Isaac Mburu, Kenya's top-ranked speed skater, make money off competitions and endorsements. In a good year, a skater can earn $3,000. Sponsors, which include a restaurant chain, telecom companies and politicians, are drawn to the sport's youth appeal and to the crowds that big races draw.

"Every organization is now asking to use our skaters to market their products," Wafula said.

Karanja and Mburu will be competing for spots in the 2015 World Roller Speed Skating World Championships, to be held this November in Taiwan.

When they return, however, they may have to find a new place to practice; the sunken parking lot is slated to be converted into a multi-story parking lot at the end of the year.

Anthony Kamunyu, acting president of the skating federation, said he is in contact with county officials on possible new skating locales. He dreams of a speed-skating track with smooth surfaces and banked corners, the kind of track Kenya's international competitors train on. There is talk of paving the area around Nyayo National Stadium to make a track.

Meanwhile, young skaters like Leleti Baikwinga will use the sunken parking lot for as long as they can to develop their skills.

The 10-year-old saw skaters one day and became entranced by their speed. Her father, a human resources specialist, bought her skates and lessons, and she loves the sport.

"When I go fast it's just a wonderful feeling," she said, smiling broadly.