Two groups have filed suit in federal court to block a rule that would allow people to carry loaded, concealed firearms in national parks.

The rule goes into effect today.

The Bush administration in December finalized a rule change to allow people to bring firearms into all national parks, including the Cuyahoga Valley National Park. Only parks in Wisconsin and Illinois are excluded from the rule.

The new rule overrides a regulation enacted by the Reagan administration that required that firearms be safely stowed and unloaded when transported through national parks.

The suit was filed by the National Parks Conservation Association and the Coalition of National Park Service Retirees. A similar lawsuit was filed in late December by the Brady Campaign, founded after the 1981 wounding of President Ronald Reagan and his press secretary James Brady during an attempted assassination. Gun supporters say that the parks are dangerous and that people have a right to defend themselves and their families.

Critics say allowing guns in the parks increases danger to visitors, park staff and wildlife.

Tom Kiernan, president of the National Parks Conservation Association, said the rule is unlawful because the Department of the Interior did not analyze its environmental effects.

The current leadership of the National Park Service and other park management professionals -- including the Association of National Park Rangers and the Ranger Lodge of the Fraternal Order of Police -- oppose the rule.

Of the 140,000 people who voiced their opinion on this issue during the public comment period, 73 percent opposed allowing loaded, concealed firearms in the national parks.