The billowing black smoke stretched at least 50 feet into the noonday sky, as searing flames from the burning pond forced the nattily dressed group of onlookers to step backward and shield their eyes from the heat.

At the edge of the flames, a huddle of 22 firemen and one woman, in rubber boots, yellow helmets and dirty, knee-length coats, wrestled to control the spray of water from two long hoses. At times, in what looked like a game of tug-of-war, the hoses seemed to be winning.

"When we tell you to turn the nozzle [so the water sprays] wide and you turn it narrow, it's an automatic lap!" the drill instructor shouted. "Who owes me a lap?"

It could be said that yesterday's exercise was the literal baptism under fire for the District's 23 newly hired firefighters, who after just six days of training begin their first assignments today at engine companies throughout the District of Columbia. But before the city's newest firefighting recruits made it to the training center on Overlook Avenue in Southeast Washington, they underwent more than the usual anxiety in finding out whether they even would get jobs.

They were originally contacted in mid-March and told to report for work, but then had their job offers retracted two weeks later. Mayor Marion Barry and Personnel Director Jose Gutierrez blamed the error on a low-level clerk, who they said inadvertently offered jobs to the applicants.

Gutierrez said that city officials were prepared to let the error pass, until they learned that 22 of the applicants were white. Gutierrez, calling the application test potentially discriminatory against blacks, retracted the job offers.

As the plight of the firefighters attracted publicity, including the personal intervention of Rep. Stanford Parris (R-Va.), Barry backtracked and rehired the recruits, admitting that "the District government made a mistake" in retracting the job offers. A 24th applicant was also offered one of the jobs, but declined it.

During yesterday's last session of their abbreviated training, the recruits took turns at the nozzle to douse a natural gas fire, flaming helicopter fuel and a simulated house fire in a blackened, smoke-filled brick warehouse with boarded windows.

Eight of the recruits live in Parris' Northern Virginia congressional district, although they will have to move into the city within six months under the District's residency law. Parris was on hand for the training session to take most of the credit for getting the recruits their jobs. "I'm very glad it worked out the way it did," he told them after they completed dousing the flames on the burning pond.

Kenneth M. Cox, vice president of Local 36 of the International Association of Firefighters also was at yesterday's session, and said, "We believe Congressman Parris was the catalyst."

The recruits themselves seemed willing to let bygones be bygones, and were just anxious to get on to the business of fighting fires. "We don't want to look back," said Paul Irvin, who became the de facto leader of the group when they were lobbying for their jobs.

Irvin quit his job as a lieutenant in the Alexandria Fire Department for the city job only to wind up unemployed when the District job was retracted. "I'm just happy that the paychecks will start rolling in," he said.

Cox and union president William E. Mole said that while the hiring snafu was resolved, problems still remain for the new recruits and for the fire department itself. The recruits had the traditional 10-week training course crammed into an intensive, six-day session because the city wnats to assign the new firefighters to the station house as fast as possible.

"As far as training, they're not ready," said Battalion Chief W. L. Mulliken. "This is an indoctrination course."

Cox said that the new recruits do not yet have their own uniforms or equipment, have had no practice driving fire trucks and have not had the emergency ambulance training that used to be given all new recruits in the 10-week program.