[JURIST] New Orleans CBS affiliate WWL-TV is reporting that martial law [Wikipedia backgrounder] has been declared in New Orleans and Jefferson Parish after levee breaks caused major flooding in the city Tuesday morning, sending waves of water through the downtown and French Quarter. Mayor Ray Nagin is estimating that 80% of the city has been flooded. WWL-TV provides continuing updates on its Katrina Blog.

12:02 PM ET – WWL-TV says that a break in 17th Street Canal Levee is 200 feet wide and water from it is gradually inundating the city.

12:16 PM ET – WWL-TV reports that martial law is now in effect in Plaquemines Parish southwest of New Orleans, where 60% of homes are said to be flooded; persons found on the streets there will be arrested. WWL-TV is broadcasting live video via KHOU in Houston. Some looting has begun in New Orleans, according to AP.

2:58 PM ET – Looting is also said to be extensive in Biloxi, Mississippi. AP has more.

5:55 PM ET – WWL-TV says state officials are putting together a plan to evacuate some 5000 inmates from the the main jails in Orleans and Jefferson parishes, both of which are threatened with flooding. Prisoners would be moved to state prisons, including the high-security Angola penetentiary [official website]. Orleans parish prisoners were originally exempted from New Orleans mayor Ray Nagin's mandatory evacuation order {JURIST report] issued Sunday.

8:35 PM ET – An Orleans Parish Prison official has told the ABC affiliate in Baton Rouge that prisoners at the OPP have rioted, have attempted to escape, and have taken s deputy, his wife and their four children hostage. The deputy had taken his family there as a refuge during Hurricane Katrina. ABC News has more.

10:18 PM ET – The Louisiana Attorney General's office has now issued some clarifications [JURIST report] concerning the martial law declarations made by local officials earlier in the day, indicating that "martial law" as such has not been legally declared in any part of the state and that no such term exists in Louisiana state law, although public officials have broad emergency powers to suspend civil liberties and commandeer property in the process of restoring order after a disaster.