CAIRO - They are a bedraggled front line, shock troops with scabbed faces and gunshot wounds, many of them boys with runny noses and sandaled feet, standing beyond police barricades with gasoline bombs, swords and stones.

They are legion, angry young men and grade school dropouts without jobs, prospects or political ideologies. They battle Egyptian police through the fog of tear gas, advancing and retreating over charred streets and shattered glass.

"We have no other choice but to fight. The political powers don't represent me," said Ahmed Rifai, pointing to a homeless boy. "A child like this shouldn't even be fighting, but he has nothing else."

The forces arrayed against President Mohamed Morsi and his party linked to the Muslim Brotherhood are many: opposition politicians, protest movements, unions and activists. But one of the most volatile threats to the Islamist-led government is embittered youths roaming like ragged armies and harboring little hope two years after the revolution that overthrew Hosni Mubarak.

That passion and despair played out across the country during a week of deadly riots. Rising dissatisfaction with Morsi was evident Friday as firebombs were tossed over the wall of the presidential palace, and demonstrators in Port Said, where more than 40 people have died, chanted for their coastal city to secede.

Echoing through the protests were voices from a disparate collection of lost boys and anarchists, including jobless waiters and laborers, university students, hard-core soccer fans known as Ultras, looters and thugs. Their ranks also comprise a new group of youths known as the Black Bloc, whose masked members despise the Brotherhood and suddenly appear in streets and alleys to besiege security forces.

The public prosecutor has characterized the Black Bloc as an "organized group that participates in terrorist acts and [commits] crimes that affect national security."

The danger of such elements has been heightened by a rising supply of arms smuggled from Libya. The cities of Port Said and Suez are rife with guns that have been turned on security forces. But the weapons of choice for most young men are rocks, pipes, Molotov cocktails and tear gas canisters fired by police, which they hurl back.

"Since the revolution everyone has a weapon," Mahmoud Mostafa said. "If I had a job, I wouldn't even be in this square. There is no opportunity for us. You can't get married. You can't find an affordable apartment. At least we were living under Mubarak. Now we don't even have that."