Defense Secretary Chuck Hagel on Tuesday evening ordered the armed services to immediately “re-train, re-credential and re-screen” tens of thousands of military recruiters and sexual-assault prevention officers as the revelation of another sex-crime scandal rocked the Pentagon.

Hagel’s order came in response to the Army’s disclosure Tuesday that a sergeant first class responsible for handling sexual-assault cases at Fort Hood, Tex., had been placed under criminal investigation over allegations of abusive sexual contact and other related matters.

Investigators are also scrutinizing allegations that the sergeant may have forced a subordinate into prostitution, according to a U.S. official familiar with the case.

Army Secretary John McHugh acknowledged Wednesday that investigators were looking into suspicions that the sergeant was involved in “pandering,” or promoting prostitution. “They’re pursuing all the possibilities,” he said in a brief interview at the Pentagon. “We have to remember they are just allegations at this point. Until the criminal investigation is completed, it’s unwise for us to speculate”

McHugh said he learned about the investigation Sunday night. Defense officials said he informed Hagel on Tuesday morning and that the defense secretary in turn notified President Obama during a meeting at the White House Tuesday afternoon.

The Army investigation comes just 10 days after a lieutenant colonel who led the Air Force’s sexual-assault prevention programs was arrested in Arlington County on charges that he groped and battered a woman in a parking lot. That incident, along with fresh statistics showing that sex crimes have become endemic in the military, sparked a furious response from lawmakers on Capitol Hill and President Obama.

Hagel warned last week that the military’s ability to recruit and perform its missions was becoming endangered by deepening public perceptions that the armed forces are unable or unwilling to cope with a sexual-assault crisis in the ranks. The latest embarrassment only made him more angry, Pentagon officials said.

“He is going to spare no effort to address this problem,” George Little, the Pentagon press secretary, told reporters Wednesday. Little said the public, lawmakers and military personnel “have the right to be outraged” about the Fort Hood investigation.

Neither the Pentagon nor the Army identified the sergeant because no charges have been filed. Special agents from the Army’s Criminal Investigation Command are probing allegations that the sergeant first class mistreated subordinates, committed assault and abusive sexual contact, and engaged in pandering, the Pentagon said in a statement.

Officials said the noncommissioned officer had been suspended from duties as an “equal-opportunity adviser” and sexual-harassment and assault prevention officer at Fort Hood, one of the Army’s biggest installations. The Pentagon did not disclose when the allegations first came to light or how many victims may have been involved.

Reaction from lawmakers was swift and livid.

“Tragically, the depth of the sexual-assault problem in our military was already overwhelmingly clear before this latest highly disturbing report,” said Sen. Carl Levin (D-Mich.), the chairman of the Senate Armed Services Committee. He said lawmakers would push ahead with a number of measures to address sexual assault in the armed forces, including changes to military law.

Rep. Niki Tsongas (D-Mass.), a member of the House Armed Services Committee, called the Fort Hood revelations “utterly abhorrent.” She added that “it has become painfully evident that saying the military has a cultural problem in regard to sexual assault and sexual misconduct is a glaring understatement.”

Rep. Howard P. “Buck” Mc­Keon (R-Calif.), chairman of the House Armed Services Committee, said that he was “outraged and disgusted” and that his faith in the military to police sex crimes was “deeply shaken.”

Sen. Kirsten Gillibrand (D-N.Y.), also a member of the Senate Armed Services Committee, said she would introduce legislation Thursday to change military law so that independent prosecutors, not commanders, would be responsible for handling sex crimes and other serious offenses. Military leaders have strenuously resisted such proposals.

“It is time to get serious and get to work reforming the military justice system that clearly isn’t working,” Gillibrand said.

In addition to directing that hundreds of sexual-assault prevention coordinators be retrained and rescreened, Hagel ordered the same treatment for all military recruiters. That move alone would affect an estimated 20,000 recruiters for the Army, Air Force, Navy and Marine Corps.

The Washington Post reported Monday that military recruiters across the country have been caught in a string of sexual-assault scandals over the past year. The Pentagon, however, does not have a grasp on the extent of the problem because it does not track sex crimes committed by its personnel against civilians before they enlist.

Last week, the Pentagon released a report estimating that the number of military personnel victimized by sexual assault and related crimes had surged by about 35 percent over the past two years despite intensive efforts to confront the problem.

The Pentagon survey estimated that 26,000 troops experienced “unwanted sexual contact” last year. Yet only a fraction of that number — 3,374 — filed sexual-assault reports with military police or prosecutors.

Military officials said most victims are reluctant to press charges because they fear retaliation from their superiors or ostracism from their units, or that investigators won’t take their cases seriously.

Lawmakers and victim advocates also blame an unwillingness among many commanders to deal with the problem forthrightly.

Members of Congress said they were outraged to learn about two cases in which Air Force generals granted clemency to convicted sex offenders, adding that the decisions would discourage other victims from reporting rape or sexual abuse.

“It is abundantly clear that the military cannot adequately handle its sexual violence crisis from within,” said Anu Bhagwati, a former Marine captain and executive director of the Service Women’s Action Network, an advocacy group. “If military culture is to transform in any meaningful way, we need to break down the doors of silence and make sure our troops who are harmed have access to the same legal remedies as all civilians whom they protect and defend.”