EL ARISH, Egypt - Egyptian troops killed as many as six Islamist militants after storming their hideout near the isolated border with Israel on Sunday, security sources and eyewitnesses said.
The troops found the militants in the settlement of al-Goura, about 15 km (10 miles) from the frontier, as they searched for jihadists who killed 16 Egyptian border guards a week ago.
The latest clash is part of a security sweep that began on Wednesday and is the biggest military operation in the region since Egypt's 1973 war with Israel. No one has claimed responsibility for killing the border guards.
It is an early test for Islamist President Mohamed Morsy, elected in June, to prove he can rein in militants whose campaign on the border worries Israel.
"People in the area supplied information that there was a group of unidentified people staying in a makeshift hut. The area was immediately raided. The group opened fire and the police returned fire," one police source said.
A senior police officer said six people had died in the fighting at al-Goura - three from bullet wounds and three more whose scorched bodies were found in the hut which was burned. Another security source said the death toll was five.
In addition to those killed, a seventh militant was seriously injured and taken to hospital in El Arish in north Sinai, said the senior policeman, who like other security sources did not give his name because he was not authorized to speak to the press.
A Reuters reporter obtained video footage of the scene showing three bodies smouldering in the burned remains of a building in the desert and armored vehicles in a line nearby.
One of the police officers said the soldiers found guns, rocket launchers, a truck and a motorcycle at the scene.
A resident of al-Goura told Reuters he had seen the lifeless bodies of two men who were not from the area, and said two other militants were arrested. "They resisted very strongly," he said by telephone. "They fired rocket-propelled grenades at the troops."
Searching another area, al-Kharouba, security forces found mortars and other weapons, said the third police source. Police said the operation to sweep the area was continuing and five men had been arrested.
The unidentified assailants who killed the border guards earlier this month also stole two military vehicles and managed to storm through a border crossing before they were killed by Israeli forces.
This prompted Israeli calls for Egypt to reassert control over an increasingly lawless Sinai and a wave of anger among Egyptians, some of it directed at Egypt's new president, who promised to restore security in the region.
Critics say Morsy risks being soft on jihadist groups because he is from the Muslim Brotherhood, a political Islamist movement that has ties to the Hamas government in Gaza and a history of hostile rhetoric towards Israel.
The Brotherhood, however, renounced violence as a means to achieve political change in Egypt decades ago.
The military crackdown began in earnest on Wednesday after unidentified men attacked several checkpoints in El Arish.
Details of the campaign have been patchy so far because the operation is spread over a wide, under-populated area and some of its inhabitants are reluctant to give details of the operation for fear of official reprisals.
The government in Cairo has brought armored vehicles, tanks and hundreds of extra troops into Sinai but its task is complicated by widespread suspicion of the authorities among local Bedouin who often carry weapons.
Further south from al-Goura, in central Sinai, unidentified gunmen shot at a checkpoint overnight and clashed with security forces there, Egyptian and international officials said.
In addition, an official for the Sinai international peacekeeping force denied that its troops had come under fire on Sunday, contradicting earlier statements of an Egyptian official who had said gunmen opened fire on the peacekeeping troops.
"We were not fired upon," said Kathleen Riley, Cairo representative of the Multinational Force and Observers (MFO) which has monitored movements of troops and military equipment along Egypt's border with Israel since their 1979 peace treaty.