Demand for water and food has been outstripping supply in Haiti's capital
Aid workers dealing with the aftermath of Haiti's earthquake face huge problems in ensuring aid is distributed widely and fairly.
Charl van der Merwe is a project manager for Oxfam, which has sent 200 staff into Haiti and has set up a logistics base in the neighbouring Dominican Republic.
He outlines the scale of the relief operation ahead.
The infrastructure in Haiti is, more or less, zero. We are, for all practical purposes, planning on the basis that we're starting from scratch.
Our staff can be fairly resourceful. When you're in that situation, you think a little bit more outside the box than you'd normally do.
Most of them went out with cash floats so they have some access to money.
We decided we were going to use Santo Domingo in the Dominican Republic as a hub, so it's going to be a key point in our supply chain.
We've made sure that we have enough money in Santo Domingo.
Most of our staff there have UK mobiles - it's not a cheap form of communication but it's all we have at the moment.
They get by and people who are travelling into Haiti have been buying stuff in Santo Domingo before they left, bringing water, food and supplies to take to the team in Haiti.
The team can understand why it's difficult to get aid out to people because there's literally nothing there.
The things you'd expect, like roads, are very, very difficult to access.
Being able to move food in a truck is just not working; people move by foot in most cases. Some areas are more or less flattened.
We're making sure we have secure distribution points where we can give out supplies in an orderly fashion.
The 2004 tsunami was "slightly easier" to deal with, Mr van der Merwe said
People have been heavily affected by this; they are traumatised, they are hungry, they are tired.
Security only really becomes an issue when people start finding distribution points are not organised well enough, with people standing in queues for days in the sun.
We're putting security in place to make sure this is done in an orderly fashion and people actually get things - so women and children get things first, because you don't particularly want them to stand in the sun all day.
I don't think anyone knows how long it'll take. The tsunami was slightly easier in a sense.
You had more infrastructure in major cities that were not close to the coastal areas.
You had a lot more options open, whereas your options are a lot more restricted in this case.
Tens of thousands are feared to have been buried in the rubble of buildings
There's the rebuilding, the clearing of all the dangerous rubble, and making sure buildings which were not demolished are actually safe and are not going to collapse in the aftermath or with aftershocks.
That's probably going to be the priority for the next couple of weeks, and then responding with massive amounts of distributions.
The scale of this one is just so complex. I used to be a town planner and thinking of rebuilding a place that's more-or-less destroyed because of an earthquake is difficult to get your mind around.
Initially we'll make sure we get the right life-saving materials to people in Haiti.
From then on, we'll start a massive rebuilding process, co-ordinated by all of the people on the ground.