Bursts of tear gas exploded in downtown Athens as police continued to battle hundreds of young self-styled anarchists rioting Sunday in major cities across Greece, according to CNN.

 In a fury over the death of a teenager killed by police on Saturday, angry demonstrations had not abated by late Sunday night.

"It at first seemed like it was calming down today, but then at 5 p.m. Athens time it kicked off again," according to Joel Brown, a CNN senior press officer visiting Athens. "There are lots of burning bins and debris in the street and a huge amount of tear gas in the air, which we got choked with on the way back to our hotel," he said.

Tourists holed up in downtown Athens hotels were told by hotel staff not to leave their rooms as police fanned out across the city, Brown said.

The U.S. and British embassies issued warnings to employees and tourists on Sunday, instructing them to avoid downtown Athens and other major cities until rioting subsides.

The police officer who fired the fatal shot 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.

Demonstrators barricaded city streets Sunday in Athens and Thessaloniki and hurled petrol bombs as they battled with police, who fought back with tear gas in the second day of rioting.

 Rampaging youths smashed storefronts and burned businesses, leaving shattered glass and burnt debris scattered across both cities.

Residents of an apartment building in central Athens were evacuated on Sunday after angry demonstrators torched a car dealership on the basement floor.

A police statement about the boy`s death said the incident started when six young protesters pelted a police patrol car with stones. The 16-year-old boy was shot as he tried to throw a fuel-filled bomb at the officers, police said.

Other youths converged on the site almost immediately.

These young people -- often referred to in Greece as " the known-unknowns" -- use texting and Web sites to organize and communicate.

Fighting between youths and police quickly erupted in other parts of Greece, including Thessaloniki, the country`s second largest city. Hundreds of youths took to the streets of the sprawling port city, and finally barricaded themselves behind the gates of a state university, where police are barred from entering.

No deaths were reported, though police say several police officers have been injured. Police say some protesters have been rounded up for questioning.

 Government officials, fearing more violence, swiftly condemned the shooting.

"An investigation is under way and those found responsible with be punished," said Interior Minister Prokopis Pavlopoulos. "Measures will also be taken to avoid such incidents again in the future."