"It is total devastation," said Sgt. 1st Class James Scalla of the Ohio National Guard, who is in the parish, told the Baton Rouge Advocate newspaper. "There is nothing. We are in survival mode."
Authorities fear the coastal parish of 68,000, may have lost as many as 1,500 of its people.
One resident in Chalmette escaped death 10 days ago when she popped through the roof of her home just ahead of rising flood waters. "I jumped out of my roof," she said.
On Wednesday, teams that retrieve the dead went to a nursing home near Chalmette. The sheriff's deputy said up to 27 bodies were inside, apparently the victims of heat and dehydration.
The parish is known for outstanding fishing, an annual spring shrimp festival and hardy residents, the report said.