ABC reporter Phillip Williams has witnessed violence and despair as he travels around Haiti's capital, Port-au-Prince, which is descending into anarchy following Wednesday's devastating earthquake.

Watch Phillip Williams' eyewitness report from the streets of Port-au-Prince.

I witnessed a person who had just been murdered in the street. He had been stripped naked and hacked to death - in fact he had not quite died when I saw him.

The crowd had decided he was a criminal - that he had attempted to rob someone - and this was retribution, this was the reaction from those in the street, because there are no structures.

The government is not functioning properly and there is little police presence. People are taking the law into their own hands, and it's a brutal law.

About half an hour later I witnessed another man burning. He had been set alight; he had been killed.

He too had been accused of robbery and in fact of having shot a woman during that robbery.

We've seen virtually no-one carrying any sense of authority and very few police. I've seen one or two policemen - they tend to be concentrated around government buildings.

We haven't seen the US troops much beyond the airport, so that element of security has not fanned out and it has not been established.

And in the absence of that security, people create their own. And it's not really security - it's insecurity - and it cannot go on too much longer.

Things are turning nasty in the streets. People are desperate - they need food, they need water, they need shelter - and most of them haven't got these basic needs.

Aid trickles out

However there is some evidence of a slight improvement in aid reaching those who need it.

We have seen points where people can get water. Obviously if they don't get water they are going to die very quickly in a hot climate.

Food is another matter, and there is very little food being distributed. The problem is there are so many people with such great needs that if they suddenly hear there is distribution of food, that place will be mobbed.

For example, I was in the Prime Minister's compound today where there are hundreds - perhaps a couple of thousand - refugees camped out there. And there was a line, hundreds and hundreds of people trying to get basics.

They were giving out US aid packages of personal toiletries and washing powder, soap, babies nappies - those sort of essentials. But they quickly ran out and they had to turn hundreds and hundreds of people away.

You can imagine the mood when they did that. These people are now getting very angry and they don't see any end to this - that's the problem.

It's not as though they see some sort of magic wand coming. They have high hopes for the Americans, but so far it's just overwhelmed them.

This is too big, this is a city around the size of Melbourne, and if you can imagine most of the houses being destroyed in Melbourne, what would the people of Australia do?

Probably they'd be in much the same situation, except this of course is a country that cannot afford and doesn't have the infrastructure to help people get out of this mess.

The Haitian government is still nominally in control, but they do not appear to be doing much and the Americans and the UN are referring to them in their decision-making process.

It is a sovereign government, so of course they have to do that, but it is not a very effective system.

There are a lot of meetings, a lot of committees, but what people need - and need quickly - is solid evidence that the aid is getting through, or at least can get through in the very near future.

And if they don't see evidence of that, I'm afraid there's just going to be more lawlessness as people get more desperate.