Six Flags announced Saturday that it has filed for Chapter 11 bankruptcy protection, dealing at least a public relations blow to Redskins owner Daniel Snyder, who took control of the theme park operator in December of 2005. In its bankruptcy filing and in a letter to employees, the company cited more than $2 billion in debt that it has been unable to pay down or refinance. All theme parks will remain open. SEE RELATED: Snyder's Red Zone LLC investment company had been a major investor in Six Flags until 2005, when it took control of the company in a proxy battle, claiming that it could turn around the struggling business. Under Snyder and his right-hand financial man, Six Flags CEO Mark Shapiro, the company's finances did improve in some areas but attendance dropped as the economy went south. To make matters worse, it became harder and harder for Six Flags to refinance its heavy debt. Six Flags was due to owe $300 million in August and wanted to refinance it but simply couldn't.