ATHENS, Greece (CNN) -- Protesters clashed with riot police and 10,000 people marched on parliament in Greece as a 15-year-old boy killed by police was buried Tuesday.
Thousands paid their respects to Alexandros Grigoropoulos at his funeral, but a small number of the protesters there grew violent at the end of the ceremony.
Riot police lined up as night fell and a reasonably peaceful candlelight vigil was held in central Athens.
Some 10,000 people marched on the country's parliament Tuesday to express their anger at the teenager's death, and also other issues like the economy, jobs, and allegations that the government is corrupt.
Groups clashed with riot police at the parliament and across central Athens.
Street riots started over the weekend after Athens police killed 15-year-old Alexandros Grigoropoulos on Saturday. Police said six young protesters pelted a police patrol car with stones, and the teen was shot as he tried to throw a fuel-filled bomb at the officers.
The shooting occurred in a neighborhood where there have been regular clashes with police, but it immediately sparked clashes and riots in Athens and Thessaloniki, the country's second-largest city. The violence then spread to other municipalities. Watch iReporter John Kountouris' videos of the violence »
The events have exacerbated the unpopularity of the ruling party and left Greek Prime Minister Konstandinos Karamanlis scrambling to shore up support. Watch crowds gathered for funeral »
On Tuesday, he met with President Karolos Papoulias and cabinet members before briefing political leaders on the country's security situation.
Opposition leader George Papandreou of the left-wing PASOK party said: "The country does not have a government that can protect its citizens, their rights, or their safety.
"I told Mr. Karamanlis that our society, our citizens are experiencing a multiple crisis: an economic crisis, a social crisis, an institutional crisis, and a crisis of values. And the government is unable to address these crises; they have lost the confidence of the Greek people." See images of anarchy on Greek streets »
Karamanlis ruled out early elections and called for all political parties to stand together against violence.
"It's our responsibility to maintain a united stance against illegal acts," he said in statement. "We must condemn in the strongest terms, with pure reason and not minced words - the violence, pillaging, and vandalism, that hampers social peace."
The government called on union leaders to cancel a national strike planned for Wednesday, fearing it could lead to further violence. But the labor movement refused, saying the action was planned before the shooting of the boy and was unrelated to it.
Cleaning crews worked for hours early Tuesday to clear the mess left by the riots, but evidence of the violence remained. In some places, entire rows of shops still have broken windows. iReport.com: Are you there? Share photos, video of rioting
The mayor of Athens asked residents not to dispose of garbage for a day because many of the city's trash bins were destroyed in the violence.
Karamanlis vowed again Tuesday that those responsible for the violence would be punished.
"I assured the president that no leniency will be tolerated in holding people accountable," he told reporters. "No one has the right to use this tragic incident as an alibi for actions of raw violence."
Athens police said 12 policemen were injured in Monday's violence and 87 people were arrested. There were 10 flashpoints across Athens where police confronted rioters, police said. Watch protesters clash with police »
Many of the young people who rioted holed up at universities, taking advantage of a decades-old rule that bars police from entering university grounds. The rule came into force after tanks crushed a 1973 student uprising protesting the ruling military junta.
The dean of Athens University resigned Tuesday as a result of the students' violent behavior.
Public and private schools and universities across the country were shut again Tuesday. Watch as iReporter witnesses the clashes
Demonstrators torched government buildings and the offices of the ruling conservative party in central Athens. They also set cars and trash containers ablaze.
Monday, young demonstrators barricaded streets in Athens and Thessaloniki and hurled gasoline bombs as they battled police. Clouds of tear gas hung over the capital as police tried to disperse the crowds.
The police officer who fired the fatal shot at the teenage boy has been charged with "manslaughter with intent" and suspended from duty, police said, adding that a second police officer was arrested Saturday on criminal accessory charges.
Government officials, including the interior minister, have condemned the shooting.
Authorities conducted an autopsy on the boy Monday in an effort to clarify the circumstances of the shooting, but the boy's family has called in their own investigators to verify state findings, the Athens coroner told CNN.
CNN's Eileen Hsieh and Phil Black, and Journalist Anthee Carassava, contributed to this report