WASHINGTON – Fitch Ratings said Tuesday that it would keep its rating on long-term U.S. debt at the highest grade, AAA, and said the outlook remained stable. But it warned that it could lower the outlook to negative if Congress fails to trim deficits.

Fitch’s rating was the best given by the three major credit rating agencies. Earlier this month, Standard & Poor’s set off a maelstrom in the stock market after it downgraded long-term U.S. debt to the second-highest level, AA-plus, for the first time.

The third agency, Moody’s Investors Service, still lists the U.S. debt at AAA but says its outlook is negative.

Fitch noted the rising proportion of U.S. debt relative to the economy. But it said it decided to maintain the AAA rating because the “key pillars” of U.S. creditworthiness remain intact, including a “flexible, diversified and wealthy economy.”

Whale stranded in California river dies

Dozens of people gathered on a highway bridge spanning the Klamath River to mourn the death Tuesday of a 45-foot female gray whale that had delighted people for more than a month after getting stranded in the northern California waterway.

No one knows why the whale took refuge in fresh water while migrating north from the birthing grounds off Baja California. Some scientists say it may have been driven inland by killer whales.

“Based on the photos and everything, her fat layer looks good, so we don’t think she starved to death. There’s something else going on,” said Sarah Wilkin, a coordinator for the National Oceanic and Atmospheric Administration.

Chlorine injures 20 at water park

At least 15 of the 20 people injured when an excessive amount of chlorine was released at a Sacramento, Calif., water park were released from hospitals, officials said Tuesday.

The conditions of the five other people could not be immediately determined.

The injured people, including nine children and three park employees, complained of burning lungs or irritated eyes after the Monday afternoon leak at the Raging Waters park.

County inspectors were focusing their investigation on a safety device in a filtration system. Initial reports indicated the system might have failed, allowing too much chlorine into the park’s wave pool.

Lightning sends 8 to Florida hospital

Officials say eight people were injured by a lightning strike Tuesday at SeaWorld’s Discovery Cove water park in Orlando.

SeaWorld spokesman Nick Gollattscheck said none of Tuesday afternoon’s injuries was life-threatening. He said three guests and five employees were hurt but that none was hit directly by lightning.

Gollattscheck said all were taken to hospitals as a precaution. He said all were conscious and alert and none of those affected was in the water.

Tobacco companies sue over warnings

Four of the five largest U.S. tobacco companies sued the federal government Tuesday over new graphic cigarette labels that include the sewn-up corpse of a smoker and a picture of diseased lungs.

Led by R.J. Reynolds Tobacco Co., and Lorillard Tobacco Co., the companies say the warnings violate their free speech rights and will cost millions of dollars to print.

The FDA refused to comment, saying it does not discuss pending litigation.

Joining R.J. Reynolds and Lorillard in the suit are Commonwealth Brands Inc., Liggett Group LLC and Santa Fe Natural Tobacco Co. Inc. Altria Group Inc., parent company of the nation’s largest cigarette maker, Philip Morris USA, is not a part of the lawsuit.