Egyptian officials say a police general was shot and killed by Islamist fighters during a security operation to reassert state control over an area on the outskirts of Cairo.

The Interior Ministry says security forces, backed by helicopters, stormed the village of Kerdasah early Thursday, firing tear gas and exchanging gunfire with what they said were terrorists.

Police say they arrested at least 41 people during house-to-house raids and are looking for about 100 more. Some are suspected of killing 11 security officers in an attack last month on the village's main police station.

Last month's violence in Kerdasah was an apparent retaliation against Egyptian state forces, which, hours earlier, had forcibly cleared two camps of supporters of deposed Islamist President Mohamed Morsi, leaving hundreds dead.

The Egyptian security operation came days after a similar raid on the town of Dalga, an area south of Cairo known to have strong Islamist support. Rights groups say the area had seen violence against minority Christians before the military retook the town.

At least 1,000 people, mostly Islamists, have been killed during Egypt's crackdown against militants and supporters of Mr. Morsi and his Muslim Brotherhood. Egyptian officials have described the campaign as a "war on terror."

Highlighting that threat, Egyptian authorities on Thursday said they defused two primitive bombs placed on the tracks of the Cairo Metro. State media said parts of the metro line were temporarily shut down while authorities investigated.