At least 12 people have been killed in clashes triggered by a deadly melee at a soccer match in Port Said on Wednesday, Egyptian authorities said Saturday.

At least seven protesters were killed in clashes with security forces that began Thursday night near the Interior Ministry in Cairo, and at least five were killed in the seaport city of Suez, according to state media.

Tensions in Cairo appeared to ease Saturday as residents and some demonstrators formed a human chain to separate the security forces guarding the Interior Ministry from a cadre of protesters intent on storming the compound, witnesses said.

The tumultuous events coincided with the rare kidnapping of two female American tourists who were released Friday night, hours after masked gunmen kidnapped them on the road that leads to St. Catherine’s Monastery, a historic landmark in the Sinai Peninsula, a military official said.

The abduction came as Egyptian demonstrators battled security forces for a second day in downtown Cairo to protest the deaths of more than 70 people killed Wednesday night in a fight between rival fans after the Port Said soccer game.

The incident in Sinai was a rare crime in a heavily traveled area that tourists for years have considered largely safe. It represented a new blow for Egypt’s beleaguered tourism industry, one of the country’s main sources of revenue, which has been reeling since the popular revolt that toppled President Hosni Mubarak a year ago.

The abduction followed a string of violent crimes in Egypt recently, including the shooting of a French tourist during the armed robbery of a currency exchange shop in the Red Sea resort town of Sharm el-Sheikh last week.

A police captain in Sinai said authorities believe that the gunmen who kidnapped the American women Friday might have been members of a Bedouin tribe trying to secure the release of fellow tribesmen detained in last week’s shooting.

The captain, who spoke on the condition of anonymity, said the kidnappers probably wanted to demand that the tribesmen be freed in return for the Americans’ release.

Last month in the Sinai Peninsula, a group of 25 Chinese workers was kidnapped by Bedouin tribesmen and then freed a day later. The tribesmen had kidnapped the workers to press their demand for the release of detainees held over bombings in the peninsula between 2004 and 2006.

Egyptians’ faith in the ability of the ruling military council to maintain order was further shaken by the post-soccer match melee and the subsequent violence in the capital and elsewhere.

Riot police guarding the Interior Ministry in downtown Cairo on Friday beat back waves of protesters with tear gas and rubber-coated bullets, witnesses said. Protesters blamed the police forces under the ministry’s supervision for not preventing the fight at the stadium in Port Said.

“We are here to break into this dirty, corrupted building, and we will stay here until we make it,” said Mina Rizk, 23, a water company employee. “This government isn’t doing anything.”