The Department of Homeland Security says an online threat against NFL stadiums this weekend is "not credible," but it issued a bulletin today to let the public know about it. DHS said a rambling threat posted on an English-language website warned that dirty bombs, delivered in trucks, would be detonated outside NFL stadiums in New York, Miami, Atlanta, Seattle, Houston, Oakland and Cleveland on Sunday, Oct. 22. A DHS spokesperson told ABC News, the department "routinely shares threat information with various public and private sector interests…This was done out of an abundance of caution. This is not a credible threat." The FBI said it would work with "our state and local partners as well as the concerned security representatives at sporting venues…The FBI routinely maintains a working relationship with the NFL and meets with them on a regular basis. This item will be part of our routine discussions this week." The NFL issued a statement saying, "Our stadiums are very well protected through the comprehensive security procedures we have in place, including secure facility perimeters, pat-downs, and bag searches." There may be some stepped-up security at stadiums this weekend out of an abundance of caution.