Six Flags, the second-biggest U.S. theme-park operator, agreed to buy its Discovery Kingdom park in Vallejo from the city for $52 million.

The company also said in a statement Wednesday that revenue at its parks has climbed 5 percent through June 3 compared with a year earlier. Attendance was unchanged at 5.9 million, hurt by six fewer park operating days than in the year-earlier period.

Six Flags, founded in 1961, earlier this year agreed to sell seven parks for $312 million to PARC Management, a closely held company run by former amusement-park executives. The sale is part of a strategy to reduce debt and increase attendance by catering to families instead of teenagers.

"We are getting more strollers and less tattoos," Chief Executive Mark Shapiro said on a conference call with analysts and investors. "Our audience is shifting, more families, less teens."

The New York-based company is seeing an increase in attendance among 24-to-49 year olds and an increase in children ages 3 to 11, Shapiro said.

Six Flags said management had agreed to run the Vallejo park and that it decided to exercise its option to purchase the amusement park, Chief Financial Officer Jeff Speed said on a conference call Wednesday with analysts and investors.

The company expects to complete the Discovery Kingdom purchase by the end of next month, Speed said. The park will add $7 million in earnings before interest, taxes, depreciation and amortization. Six Flags has been managing the park since 1997.