Athens rocked by 7th day of clashes

ATHENS, Greece (CNN) -- Youths smashed windows and threw rocks at police in central Athens Friday, the seventh day of clashes that erupted after a police officer killed a 15-year-old boy last Saturday.

Protesters, described as mostly students, were seen smashing the glass doors of a Citibank, throwing a metal barricade at police lined up along a street and scuffling with police wearing white helmets.

Many of the officers were wearing riot gear. One image showed a substance that looked like blood on a curb.

Tourists were advised to stay in their hotels while thousands of demonstrators shouted and taunted police outside.

Journalist Anthee Carassava said the protests were expected to continue into the evening. Watch how the unrest could cause a crisis »

The official ballistics report from last weekend's shooting was expected to be released Friday.

The teen who was shot and other youths had been throwing stones at a police patrol car.

The riots that followed soon became an outlet for simmering anger about the economy, education and jobs. The unrest is threatening the government's hold on power, with some opposition groups calling for fresh elections.

The two officers involved in Saturday's shooting were remanded into custody Wednesday pending trial. One is charged with premeditated manslaughter and the other with acting as an accomplice.

On Thursday, their lawyer, Alexis Kougias, said initial results from a ballistics test show the officer did not fire directly at the teen. Instead, the bullet ricocheted off another object before hitting the boy in the chest.

Officials fear that if the ricochet theory pans out, it could inflame tensions and spark more riots.

The initial examination shows the bullet taken from the victim was scraped and deformed on one side, Kougias said. That indicates the bullet was one of two warning shots fired by police into the air, which then ricocheted and hit the boy.

A police statement issued soon after the shooting said the teen and five other youths had been throwing stones at a police car when the incident took place. But a statement posted Friday but dated with Sunday's date said that 30 people were throwing things at the vehicle.

Carassava said many security experts and citizens believe the police did not respond quickly enough to contain the protests after the shooting, allowing them grow out of control.

The unrest Friday followed a day of relative calm on Thursday that allowed many Athenians to return to work for the first time in days.

Hundreds of students have refused to return to school and several of them protested Thursday at local police precincts. Several student groups staged sit-ins along 10 major streets in Athens, at 120 high schools across the country, and at 15 universities.

At the Athens Polytechnic University -- a major flashpoint with clashes between anarchists and police -- municipal crews were able to clear the streets for the first time in days. So much debris was in the streets from the protests that in some places it was half a foot deep.

Anarchists stopped the crews from clearing two streets and taking away burned-out vehicles, saying they wanted to use the cars for barricades in what they said would be street fights Thursday night.

The only major clash Thursday was outside the large Koyrdallos prison in Athens, where youths faced off violently with police.

Shopkeepers and businessmen seemed determined to reclaim their city from the protesters who have wreaked havoc and caused destruction across Athens. Since Wednesday, groups of merchants have been seen confronting hooded, masked youths involved in the protests, and even fighting with them.

Journalist Anthee Carassava and CNN's Eileen Hsieh contributed to this report.

All About Greece • Athens