Witnesses told Nour that the armed men were young people from the local neighbourhood and that government and Ethiopian troops were regularly attacked there.
Nour said: "We found a dead young man who was killed during the clashes. Some youngsters were dragging him, saying he is a policeman but ... a spokesman for the government affirmed that one policeman was injured.
"Witnesses at the scene affirmed that seven people have been injured during the fighting and another three, including the policeman, have been killed."
The ambush is the latest in a series on Somali government and Ethiopian forces and follows an attack on two police stations in Mogadishu.
Seven people were injured when gunmen fired rocket-propelled grenades at two police stations in Mogadishu and fired machine-guns at officers stationed outside.
"In Howlwadag, two policemen and three civilians were wounded while in Wardigley, a civilian and a policeman were injured," said Ali Nur, a Somali police officer.
The Somali government blames the attacks on fighters from the Islamic Courts Union, which was forced from Mogadishu in December last year and promised to continue a guerrilla war against the government and its Ethiopian backers.
Islamic Courts fighters have pulled back from Mogadishu further into the south of Somalia, where they have been attacked by Ethiopian and US air raids.
Abdirahman Dinari, a government spokesman, said: "We will make sure such individuals are filtered from society and apprehended."
Leaflets allegedly from the Islamic Courts were circulated in Mogadishu over the weekend, saying residents should avoid collaborating with Ethiopian forces or face "losing lives and property".
Dinari called the leaflets "cheap propaganda".
He said: "It will not work. I urge the people to work with the government, and in particular the police, in order to protect their lives."
He also said that Islamic Courts fighters were regrouping and that the Somali government lacked the troops, training and weapons to deal with them.
"We need the support of the international community to deploy forces and assist us in securing the country," said Dinari.
"I urge the people to work with the government, and in particular the police, in order to protect their lives"
Although the government claimed Mogadishu from the Islamic Courts, the government faces opposition from other groups including various clan militias.
In Ethiopia, Meles Zenawi, the Ethiopian prime minister, has said Ethiopia will pull a third of its troops out of Somalia in the next two days.
But although international diplomats agree Somalia will need a peacekeeping force, it is unclear where the troops will come from.
As Ethiopian forces began to pull back from Somalia, Zenawi said that the Islamic Courts were no longer a military threat but that they could regroup unless there was reconciliation among Somali clans.
He said: "If the politics are not right, then they can in the future rebuild their capacity."
US military officials in Doha, Qatar, said Somalia could return to chaos in just four months if international peacekeepers are not quickly deployed to replace the departing Ethiopian troops.
They said a "power vacuum" was developing in Somalia with the departure of the Ethiopian troops and reports that the army is being weakened by malaria.
The US military said it stationed a US Navy carrier battle group off the coast of Somalia and mounted an air raid in the campaign against the Islamic Courts last year, but it has no plans to increase its role in the country.
"When Ethiopia pulls out, we'll reduce our presence there", US officials said.