Egyptian security forces have clashed with protesters demanding an end to military rule.

Hundreds of protesters in Cairo hurled rocks and firebombs at military police, Friday, who responded by using water cannons and firing shots into the air.

Witnesses say the unrest began late Thursday after an activist posted images online that appeared to show a demonstrator who had been beaten up by military authorities after being arrested.

The images prompted other Egyptians to rush to the scene of a sit-in that has been underway outside of the Cabinet building since November. Protesters at the site have been demanding Egypt's military rulers immediately transfer power to a civilian authority. Several people were wounded in Friday's clashes.

The violence comes as Egyptians await the official results of the second round of parliamentary elections held this week. Islamist parties appeared to be extending their already overwhelming electoral gains.

Election officials are expected to announce final results Friday or Saturday.

The Muslim Brotherhood's Freedom and Justice Party and the ultraconservative al-Nour Salafi Islamist party, which want Egypt to adhere to the principles of Islamic law, dominated the first round of voting in late November.

A third round of elections covering the remaining nine provinces will take place in early January.

The parliamentary elections are Egypt's first since a popular uprising ousted long-time President Hosni Mubarak in February.

Elections for parliament's less powerful upper house will begin in late January and finish in March, after which the assembly will write a new constitution.