CAIRO — Soldiers stormed a protest camp outside Egypt’s Cabinet building, expelling demonstrators calling for an end to military rule, just as officials were counting votes today in the second round of Egypt’s parliamentary elections.

The clashes underlined simmering tensions between activists and security officers and threatened to ignite a new round of violence after a mostly peaceful vote Wednesday and Thursday in an election considered the freest and fairest vote in the country’s modern history.

Clashes erupted as demonstrators were camped out in front of the Cabinet building, demanding that the country’s military rulers transfer power immediately to a civilian authority. The sit-in was in its third week.

One activist posted a photo online of a female protester beaten in the clashes, and others said they were briefly detained by military police. It was unclear how many protesters remain in military police custody.

On his Twitter account, leading reform figure and Nobel Peace Prize winner Mohamed ElBaradei condemned the violence.

“If the sit-in broke the law, isn’t the cruelty and brutality used to break it up a greater violation of all human rights laws? This is not how nations are managed,” he wrote.

The military took over after longtime President Hosni Mubarak was ousted in a popular revolt in February. Rights groups and activists charge that the military is carrying on the practices of the old regime, including arresting and beating dissidents.

Protesters at the Cabinet building said the clashes began Thursday evening after soldiers severely beat a young man who was taking part in the sit-in.

Hundreds of people rushed to join the protest after online video and photos showed people carrying the wounded man. Witnesses accused military police of snatching the man from near the sit-in and beating him inside parliament, near Cabinet headquarters. Then protesters threw rocks and firebombs at military police.

Activist Hussein Hammouda said the military responded by throwing rocks, pieces of glass and aiming water cannons from inside the gates of the nearby parliament building.

“Tensions between the people and security officers is so enflamed that anything that happens just blows up,” said Hammouda, who resigned from the police in 2005.

Egypt’s state news agency said at least four wounded people were taken to a nearby hospital and that a fire had broken out in a government building.