Riot police clashed with demonstrators outside Parliament Wednesday as a general strike paralyzed Greece, shutting down schools, hospitals and international flights and raising pressure on a fragile government reeling from four days of riots. The lawyer for the two officers accused in the fatal shooting of a teenager that set off the unrest said ballistics show 15-year-old Alexandros Griogropoulos was killed by a ricochet and not a direct shot. Lawyer Alexis Cougias said the report corroborated the officers' account that they fired warning shots and did not shoot directly at the boy. One officer has been charged with murder and the other as an accomplice. They were to appear in court later in the day. Authorities have not made the ballistics report public. The rioting and demonstrations were set off by anger at the shooting but fed by months of widespread discontent with the conservative government of Prime Minister Costas Karamanlis, whose party holds a majority of a single seat in the 300-member parliament. More than 10,000 people marched through the center of the city to protest the conservative government's economic policies. Riot police began firing tear gas when a small group of youths threw Molotov cocktails and rocks at them near Parliament in the center of the Greek capital. Flights to and from Athens International Airport were canceled, and public hospitals across Greece were operating with a skeleton staff. Schools and universities were closed. Karamanlis has faced growing opposition over changes to the country's pension system, privatization and the loosening of state control of higher education, which many students oppose because they feel it will undermine their degrees. The government's support has dropped lower as gangs of youths maraud through cities across the country, torching businesses, looting shops and setting up burning barricades across streets. Storeowners accuse riot police of leaving their businesses unprotected as rioters smashed and burned their way through popular shopping districts. Although police have fired volley after volley of tear gas when attacked by rock- and Molotov cocktail-throwing protesters, they held back when youths turned against buildings and cars. Local media reported early Wednesday that groups of civilians had begun taking matters into their own hands, confronting looters in the western city of Patras and the central city of Larissa. Opposition Socialist leader George Papandreou claimed the conservatives are incapable of defending the public from rioters. But Karamanlis has so far ignored mounting calls for him to resign and call early elections. An opinion poll for the conservative daily Kathimerini published Wednesday found 68 percent of Greece believe the government mishandled the crisis - including nearly half of respondents who voted for Karamanlis' conservative party in general elections last year. Only 18 percent approved. The Public Issues survey was based on a sample of 478 people questioned on Monday and Tuesday and had a 4.5 percent margin of error. "The government wanted us to postpone this protest, but they are the ones who have to do something to stop this violence and to improve the quality of our lives," said one demonstrator, drama student Kalypso Synenoglou. Greece has a long legacy of activism; it was a student uprising that eventually brought down a seven-year military junta in 1974. Tensions persist between the security establishment and a phalanx of deeply entrenched leftist groups that often protest globalization and US foreign policy in the Middle East and elsewhere. The groups have now evolved into various mainly youth factions that claim to fight trends ranging from globalization to police surveillance cameras. Their impact is usually limited to graffiti and late-night firebomb attacks on targets such as stores and cash machines. Amnesty International accused Greek police of heavy-handed tactics against protesters, saying police "engaged in punitive violence against peaceful demonstrators" instead of focusing on rioters. Authorities are investigating reports officers used their pistols to fire warning shots in the air during Tuesday's riots.