TIMELINE: Events in Greece since teenager's shooting

(Reuters) - Students pelted police with firebombs and stones in Athens on Friday in new clashes that first broke out over the police killing of a teenager.

Here is a timeline of events.

DEC. 6 -- A police officer shoots dead 15-year-old Alexandros Grigoropoulos in central Athens. The policeman says he fired warning shots but witnesses say he aimed at the victim.

-- Thousands protest in Athens hours later, throwing petrol bombs, smashing shop windows and setting fires. Police clash with rioters using teargas, choking the capital's center.

-- Riots spread across Greece, to the northern cities of Thessaloniki, Komotini and Ioannina as well as the tourist resorts of Crete and Corfu.

-- Interior Minister Prokopis Pavlopoulos makes a public apology and later submits his resignation, which is rejected by Prime Minister Costas Karamanlis.

-- Two policemen are arrested over the teenager's death.

DEC. 7 -- Thousands of demonstrators chanting "Killers in Uniform" march for a second day in Athens, Thessaloniki, Crete, Patras, Corfu and Ioannina.

-- Karamanlis sends a letter to the dead teenager's family, expressing his sorrow and promising the culprits will be punished. Pavlopoulos appeals for calm.

-- One police officer is charged with murder and another with abetting him.

-- The mayor of Athens postpones the launch of Christmas festivities.

DEC. 8 -- Demonstrators launch a third day of protests and occupy university buildings. Dozens of marches bring Athens to a standstill as shop owners count the damage.

-- Hundreds battle with police in more than 10 cities across the country, including Thessaloniki.

-- Thousands of demonstrators march in the evening through the heart of Athens, damaging and looting scores of shops, destroying banks and attacking ministries. The city's huge Christmas tree goes up in flames.

-- Karamanlis holds government meeting and Pavlopoulos says there will be no tolerance for such events.

DEC. 9 -- The opposition socialist party calls for elections to end the four days of protests.