Updated at 10:45 a.m. Friday: Revised to include more context about the vice unit.

In her first major move as Dallas police chief, U. Renee Hall on Thursday temporarily dismantled the department's vice unit after discovering "serious issues" and reassigned its 20 officers.

The chief has not publicly detailed what led to her decision to overhaul the unit that oversees prostitution and gambling investigations.

"There are some serious issues that need to be addressed because there are more questions than answers following my initial assessment," she said at a news conference Thursday evening.

The vice unit's specialized officers will be reassigned to five other "critical enforcement" areas, such as domestic violence and robberies.

New investigations that the vice unit would typically handle will fall to patrol officers and other units, Hall said. It is unclear what will happen to open cases.

"We are responsible to the residents of this community," she said. "Service is first. Accountability is important, and we have to operate within the highest level of integrity."

The chief has moved Assistant Chief Gary Tittle from the strategic deployment bureau, which houses the narcotics and vice units, to the patrol division. Assistant Chief Paul Stokes, who used to oversee the patrol division, has been moved to the strategic deployment bureau.

But Hall said Thursday that it would be unfair to blame anyone for the vice unit's issues, adding that it's too early to say whether anyone will face disciplinary action.

She has hired members of the International Association of Chiefs of Police to conduct an impartial analysis of the vice unit and help remedy its problems.

Dallas City Council Member Adam McGough, who chairs the public safety and criminal justice committee, said Thursday that like the chief, he doesn't want to jump to conclusions about the vice unit.

"I'm going to wait and let the facts come out," said McGough, adding that he supports Hall's plans to re-evaluate and restructure the department.

Dallas Police Association President Michael Mata also declined to speculate about what the chief found during her initial review.

"The men and women of the vice unit are of the highest integrity, and they have set the standard in dealing with vice offenses and investigations in North Texas," Mata said.

One of the unit's former officers came under scrutiny two years ago, when he was sentenced to federal prison for giving a prostitute protection in exchange for sexual favors and coaching her to say she was his confidential informant if questioned about the relationship.

Police officials, however, testified then that department policy prohibited officers from meeting informants without another officer present. An undercover vice detective testified that it was rare for his colleagues to even have informants in prostitution cases.

The ex-cop, Jose Luis Bedoy, was fined $25,000 and sentenced to 18 months in federal prison.

Hall, who joined the force in September, is conducting a top-to-bottom review of the Police Department. Beyond the vice changes, additional shakeups are expected in the coming weeks, including a new organizational structure and leadership staff.

Her command staff is likely to shrink — a move that could result in demotions.

Hall's predecessor, Chief David Brown, had nine assistant chiefs and more than a dozen deputy chiefs at one point last year. The police associations often criticized his large command staff, calling it inefficient and unnecessary.

A draft copy of Hall's organizational chart shows three assistant chiefs and seven deputy chiefs.

The department currently has seven patrol divisions, but that could change, too. Hall's chart divides the city into four patrol divisions: central, west, east and south. Some of those divisions would be broken into smaller patrol areas.