SAN JOSE — The top two executives at the agency that manages the Santa Clara County Fairgrounds have abruptly left the organization, according to county and fairgrounds officials.

The Fairgrounds Management Corp.’s five-member board put Executive Director Delana Romero on paid administrative leave and accepted CFO Howard Thomas’ resignation during a closed-door personnel meeting late last week, according to fairgrounds spokesman Steve Stagnaro.

Neither Romero nor Thomas returned calls seeking comment. FMC Board President Mary Bartlett, who took over Romero’s duties as interim executive director in her absence, also was unavailable.

County and fairgrounds officials were tight-lipped about the reasons behind Romero’s leave, calling it a personnel matter. Her contract ends this month, before the next fairgrounds board meeting.

Rob Coelho, an attorney with the County Counsel’s Office, said only that her leave involves “an incident that is being investigated.”

“Right now it’s a personnel issue that’s being conducted and it is at its relatively early stages,” Coelho said.

Santa Clara County Board President Dave Cortese said the matter was the basis for a special meeting held on Tuesday by the fairgrounds board.

Sources familiar with the investigation said the issue involved whether the two executives mishandled allegations of financial improprieties involving another fairgrounds staffer, who has not been identified. The amount of money involved was said to exceed $100,000, the sources said.

“Something not good,” Cortese said.

The Fair Management Corp. board accepted Thomas’ resignation at the same series of closed meetings.

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Recently appointed fairgrounds board member Tyson Greaves cautioned against jumping to conclusions about the executives’ departures.

“I would encourage people to suspend judgment until all the facts are in,” Greaves said.

Coelho said his department is not conducting the investigation, and a spokesman for the sheriff’s office said he could not comment on any pending matters before an outcome is delivered.

Stagnaro said Thomas had planned on retiring for some time but did not know why he opted to resign instead.

“There was general knowledge that he had already stuck around a year longer than he had wanted,” Stagnaro said. “I honestly don’t know if the timing was coincidental.”

The Fairgrounds Management Corporation is contracted to run the facility by Santa Clara County, which owns the 150-acre site on Tully Road near the Monterey Highway in San Jose.

Romero, 63, has been involved with the fair for decades, and was promoted from fair manager to executive director in 2012. The job involves overseeing operations at the fairgrounds and events center, the annual county fair, the off-track betting facility and other tenants.

As CFO, Thomas handled the financial side of the operation. He held the position for nearly six years.

According to Roger Mialocq of Harvey Rose Associates, the county’s contracted auditor, they have done high-level examinations of how FMC is doing financially overall, but have never been asked to do the sort of management audit that might reveal specific improprieties within a given department.

FMC was the subject of a scathing grand jury report in 2011, which found that it “does not employ sound business practices,” with a board that “does not demonstrate the business acumen necessary to effectively oversee FMC.”

“The fairgrounds for many, many years had been having a difficult time,” Mialocq said. “They often operate on a break-even basis, just barely making it.”

But that’s improved in recent years, said Cortese, although he still questioned FMC’s apparent lack of ability to draw people to the site.

“They figured out how to stay in the black and have learned to do pretty robust programming for the facility, and I’ll give them a thumbs up there,” Cortese said. “But where the arrow goes down is the fair itself. It’s supposed to be the granddaddy of all events but it’s just pathetic. They seem to be trying to go hand-to-mouth from one event to the next without any vision or inspiration toward putting on a first-class event.”