Greg Henderson is a pathologist from New Orleans.
After Hurricane Katrina struck he stayed in the city and has set up a makeshift hospital at the Ritz Carlton Hotel, along with fellow doctors who were attending a medical conference.
From there he sent updates to his friends on the desperate situation in the flooded city. One of those friends, S Syer, from Dallas, sent Mr Henderson's latest update to the BBC News website.
Personally, my family and I are fine.
My wife and two young girls are now safe in Jackson, Mississippi, and I am now a temporary resident of the Ritz Carlton Hotel in New Orleans.
In addition, this hotel is in a very old building on Canal Street which sustained little damage.
Many of the other hotels sustained significant loss of windows and we expect that many of the guests may be evacuated here.
Overnight on Monday the water arrived. Now Canal Street, true to its origins, is indeed a canal.
The first floors of all downtown buildings are underwater.
I have heard that Charity Hospital and Tulane Hospital are limited in their ability to care for patients because of flooding.
Ochsner is the only hospital that remains fully functional.
However, I spoke with them and they too are on generators and losing food and water fast.
The city has no clean water, no sewage system, no electricity, and no real communications.
Bodies are still being recovered, found floating in the floods.
We are worried about a cholera epidemic. Even the police are without effective communications.
A group of armed police are here at the hotel trying to exert some local law enforcement.
This is tough because looting is rampant. Most of it is not malicious looting.
These are poor and desperate people with no housing, no medical care, no food and no water trying to take care of themselves and their families.
Unfortunately, some people are armed and dangerous. We hear gunshots frequently.
Most of Canal Street is occupied by armed looters who have a low threshold for discharging their weapons.
We are still waiting for a significant National Guard presence.
The health care situation here has dramatically worsened overnight. Many people in the hotel are elderly or small children.
Many others have unusual diseases.
Multiple medical problems
We have set up a makeshift hospital in the French Quarter Bar in the hotel.
There is a team of about seven doctors and pharmacists. We anticipate that this will be the major medical facility in the central business district and French Quarter.
Our biggest adventure today was raiding the Walgreens on Canal Street under police escort.
Infection and perhaps even cholera are anticipated major problems
The pharmacy was dark and full of water. We basically scooped entire drug sets into garbage bags and removed them.
We are anticipating dealing with multiple medical problems and acute injuries.
Infection and perhaps even cholera are anticipated major problems.
The biggest question to all of us is: Where is the National Guard?
We hear jet fighters and helicopters overhead, but there is no real armed presence, and hence the rampant looting.
There is no Red Cross and no Salvation Army.
We are under martial law, so a return to our homes is impossible.
I don't know how long it will be and this is my greatest fear.
The greatest pain is to think about the loss, and how long the rebuilding will take.
That, and the horror of so many dead people .