GRAND PRAIRIE -- Shares of Six Flags Entertainment surged 8 percent on Monday after the amusement park operator reported a smaller first-quarter loss as park attendance rose 41 percent over last year.Six Flags said about 1.8 million guests came to its parks during the first three months of the year, typically its slowest period of the year. It attributed about half the gains to some school districts scheduling spring breaks in March instead of April. The company added that guests spent more money at the park, and Six Flags was more successful at selling season passes.The company, which operates Six Flags Over Texas and Hurricane Harbor, said it lost $62.5 million, or $1.23 per share, in the latest quarter after losing $115.1 million in the first quarter of 2012. Revenue grew 32 percent, to $87.5 million.Shares of Six Flags (ticker: SIX ) gained $5.86 to $77.11 a share.Analysts have cited Six Flags' efforts to sell season passes and new attractions as reasons for optimism about its business. The company said revenue from admissions rose 41 percent to $41.5 million, and revenue from food and merchandise increased 33 percent to $32.8 million.