Along with the hundreds missing from Haiti's earthquake, apparently so too have the Haitian National Police (HNP), said the spokesperson for the United Nations peacekeeping force in New?York?Thursday.

"The National Haitian Police are not visible at all," said David Wimhurst via a video conference from Port-au-Prince, the capital of Haiti. "They've simply vanished."

"Don't forget that they're Haitian too and their family homes have been smashed up or destroyed and their family members have been killed or destroyed, so they're acting to look after their nearest and dearest," he added.

With no visible presence of the police force, the United Nations and the international community have been tasked with securing law and order since the 7.0-magnitude earthquake struck on Tuesday.

Currently, the United Nations has 3,000 police and military peacekeepers in Port-au-Prince and by later Thursday 3,500 troops form the United States are expected to arrive.

The UN mission in Haiti, known as MINUSTAH, can request additional security support from the UN Secretariat should security deteriorate, but so far it's not necessary, said Wimhurst.

"We will, if necessary, bring troops or police from the outside areas into Port-au-Prince," he said.

However, while the security situation appears to be relatively calm with just a few reports of looting, Wimhurst said, tensions are beginning to heat up.

Thousands of Haitians have been left to fend for themselves. With no shelter, they have taken to the streets, sleeping among slabs of broken concrete. Tons of medicine, food and tents have been slowly arriving in Haiti but access has been difficult, said Wimhurst.

With limited assistance, many are beginning to get "angry and impatient", said David, adding that if time goes by with little progress, "tempers might become frayed."

Kim Bolduc, the humanitarian coordinator in Haiti, also said there is a risk of social unrest. Haitians on the streets are asking for help to gather bodies, dispose of them and carry the injured to medical facilities, she said.

She noted that once the World Food Program begins to distribute food the situation might calm down. There is enough relief support for about a week, she added.

"People are in a state of shock," she said. "They're waiting for something to happen."