One inmate was tossed out of a second-story window and three others were also injured yesterday morning during a fight at Lorton Reformatory's Youth Center 2 -- the second disturbance there in 13 hours, corrections officials said.

The fight, apparently provoked by the earlier disturbance, broke out at 8:30 a.m. among 30 to 40 inmates, some armed with broken chair legs and sections of bed frames, according to Leo Gibs, a spokesman for the D.C. Department of Corrections. Prison guards used a canister of tear gas to bring the fight under control by 9 a.m., he said.

"Everything is in control," Gibs told reporters outside the prison around noon yesterday. The inmates were herded onto a football field, and a shakedown was conducted.

It was the second violent incident within a day at the District-run prison in southern Fairfax County. About 7:30 p.m. Thursday, violence flared among a few inmates and escalated to a similar-sized group housed in different dormitories at the youth center, Gibs said.

Five inmates were injured in Thursday's fight, two by corrections officials using birdshot to quell the disturbance and to cover an injured inmate running for help toward a tower. He said prison officials did not know what started the fight.

D.C. General Hospital spokesman Millree Williams said four inmates were treated for injuries received during the first disturbance -- two for birdshot wounds, one for lacerations and one for minor injuries.

Of those injured yesterday morning, Williams said, three were taken to the hospital and treated for injuries, including head trauma and lacerations. He said the inmate who was thrown out the window was listed in stable condition. None of the inmates was identified by name, and no one else was seriously hurt in the disturbances, he said.

John F. Herrity, chairman of the Fairfax County Board of Supervisors and a longtime Lorton Prison critic, charged yesterday that the county was not notified quickly enough of Thursday night's disturbance and called for an investigation. He said later that D.C. Mayor Marion Barry had agreed to an investigation.

Herrity said the county was informed a half-hour after the disturbance had begun. "This is totally and completely unacceptable," he said, standing outside the youth center. "That could be the difference between life and death."

Fairfax police spokesman Warren Carmichael said that although the county's Emergency Operations Center log showed that Lorton officials contacted them at 7:43 p.m., he said the county was informed, by a D.C. official, that the disturbance had started at 7:15 p.m.

Gibs denied that account, saying the county was notified within five minutes. He said the fight started at 7:35 p.m. and Fairfax and Prince William officials were notified at 7:40 p.m.

Herrity said prison officials may be referring to the point when the fight escalated, not when it started. The county needs to be informed when "something has gone down," however minor, he said.

Under an agreement with the prison, officials are to notify Fairfax County police of "virtually everything," including overdoses, illnesses and injuries inmates receive playing basketball, Carmichael said.

Carmichael said yesterday's disturbance, which was reported promptly, was described to police as "a major uprising." About 15 Fairfax officers patrolled the perimeter, and others circled the complex in a helicopter.

Youth Center 2, which houses men aged 18 to 22 who were sentenced under the Youth Offenders Act, and the larger Youth Center 1 have been scenes of a number of violent incidents in recent years. The capacity of Youth Center 1 is 250. Gibs said prison officials would not reveal the current population.

Staff writers Nancy Lewis and Elsa Walsh contributed to this report.