The people spoke on condition of anonymity to The Associated Press because the deal is still pending approval from the NBA Board of Governors.
One person said the Maloofs are selling all 65 percent of their share for $525 million to Hansen, who will move the team to Seattle and restore the SuperSonics name.
The sale figure is a total valuation of the franchise, which includes relocations fees. Hansen's group also is hoping to buy out other minority investors.
The Maloofs will receive a $30 million non-refundable deposit on Feb. 1, according to the deal, one person said. They will still be allowed to receive other offers until the league approves the sale.
Sacramento Mayor Kevin Johnson said last week he had received permission from NBA Commissioner David Stern to present a counteroffer to league owners from buyers who would keep the Kings in Sacramento.
The deadline for teams to apply for a move for the next season is March 1.
Johnson said in a statement late Sunday night that the city remains undeterred despite the agreement with the Seattle group.
"Sacramento has proven that it is a strong NBA market with a fan base that year in and year out has demonstrated a commitment to the Kings by selling out 19 of 27 seasons in a top 20 market and owning two of the longest sellout streaks in NBA history," Johnson said.
"When it comes to keeping the team in our community, Sacramento is playing to win. In particular, we have been focused like a laser on identifying an ownership group that will both have the financial resources desired by the NBA and the vision to make the Kings the NBA equivalent of what the Green Bay Packers have been in the NFL."
In a saga that has dragged on for nearly three years, Johnson and Sacramento appear to be facing their most daunting challenge yet.
Hansen, a Seattle native and San Francisco-based investor, reached agreement with local governments in Seattle last October on plans to build a $490 million arena near the city's other stadiums, CenturyLink Field and Safeco Field.
As part of the agreement, no construction will begin until all environmental reviews are completed and a team has been secured.
Hansen's group is expected to pitch in $290 million in private investment toward the arena, along with helping to pay for transportation improvements in the area around the stadiums.
The plans also call for the arena to be able to handle a future NHL franchise.
The remaining $200 million in public financing would be paid back with rent money and admissions taxes from the arena, and if that money falls short, Hansen would be responsible for making up the rest.
Other investors in the proposed arena include Microsoft Chief Executive Steve Ballmer and two members of the Nordstrom department store family.
Hansen's goal has been to return the SuperSonics to the Puget Sound after they were moved from Seattle to Oklahoma City in 2008.
Asked in September if he could envision a team being in Seattle for the 2013 season, Hansen was cautious about finding an option that quickly.
The Kings' sale price would top the NBA-record $450 million the Golden State Warriors sold for in July 2010.
The Maloofs backed out of a tentative $391 million deal for a new downtown arena with Sacramento last year, reigniting fears the franchise could relocate.
Johnson and the Kings broke off all negotiations in the summer with the team's owners, who said the deal didn't make financial sense for the franchise.
In 2011, the Kings appeared determined to move to Anaheim before Johnson convinced the NBA to give the city one last chance to help finance an arena.
At one point, Johnson seemed so certain the team was gone he called the process a "slow death" and compared the city's efforts to keep the Kings a "Hail Mary."
Johnson made a pitch to the NBA Board of Governors in April 2011, promising league owners the city would find a way to help finance a new arena to replace the team's current outdated suburban facility. That pitch bought the Kings time, before the brokered deal between the city and the Maloofs fell apart last year.