Armed central security police showered Tahrir Square with tear gas canisters and fired bullets into the air as several thousand demonstrators amassed and called for the resignation of Egypt's de facto head of state, Field Marshall Mohamed Hussein Tantawi.
Some members of the crowd tore up paving stones and threw them towards police lines.
The Guardian witnessed successive volleys of tear gas launched into thesquare and surrounding streets by government forces, including towards areas where ambulances had congregated to treat the wounded. Injured protesters, mostly with head wounds and gas inhalation, were carried to safety on the shoulders of fellow demonstrators.Al Jazeera reports that the protesters appear as determined now as they were earlier this year.
The clashes near the interior ministry on Tuesday evening were triggered by family members of the more than 840 people who were killed during the Egyptian uprising in February.
Tahrir Square was the epicentre of the nearly three-week-long uprising that ousted former president Hosni Mubarak.
Al Jazeera's Ayman Mohyeldin reporting from Cairo said at least eight people had been injured.Various photographs, including this one and this one, provide a glimpse of what the square looks like.
My friend Kim Fox, who is teaching at the American University of Cairo, tweeted her encouragement to the protesters a short time ago, noting that it is in the middle of the night that the" riot police love to do their dirtiest work at this hour, so be strong and resilient."
To this point, international leaders have remained quiet about the recent protests, which are gaining in intensity.