[msnimje]

What about the Gretna Sheriff blocking the Crescent City Bridge thereby trapping the people in New Orleans?

[Magnolia]

We Shut Down the Bridge

[GretchenM]

"WE SHUT DOWN THE BRIDGE" [trapping evacuees inside New Orleans] [John Podhoretz] National Review Online September 9, 2005
"UPI ["Cops Trapped Survivors in New Orleans"] has the police chief of Gretna, Louisiana, admitting that he closed off one of the major arteries out of New Orleans on Monday, before the storm hit." / end excerpt

[tarheelswamprat]

What about the Gretna Sheriff blocking the Crescent City Bridge thereby trapping the people in New Orleans?

That action did not "trap the people" in New Orleans. There were plenty of other routes out of the city. His action simply prevented the looting and trashing of his own city and parish, and protected the lives and property of his own citizens.