People sit, hours before riot police use tear gas and pressurized water to quash a peaceful demonstration by hundreds of people staging a sit-in protest to try and prevent the demolition of trees at an Istanbul park. Police moved in at dawn Friday to disperse the crowd on the fourth day of the protest against a contentious government plan to revamp Istanbul's main square, injuring a number of protesters. The protesters are demanding that the square's park, Gezi, be protected. (AP Photo) #

A Turkish riot policeman sprays tear gas as people protest against the destruction of trees in a park brought about by a pedestrian project, in Taksim Square in central Istanbul, on May 28, 2013. (Reuters/Osman Orsal) #

A Turkish riot policeman sprays tear gas as people protest against the destruction of trees in a park brought in Taksim Square in Istanbul, on May 28, 2013. (Reuters/Osman Orsal) #

In this Thursday, May 30, 2013 photo, a man wears a make-shift gas-mask hours before riot police used tear gas and pressurized water to quash a peaceful demonstration by hundreds of people staging a sit-in protest to try and prevent the demolition of trees at an Istanbul park. (AP Photo) #

Protesters clash with Turkish riot policemen on May 31, 2013 during a protest against the demolition of the Taksim Gezi Park in Istanbul. (Gurcan Ozturk/AFP/Getty Images) #

Riot police use tear gas to disperse a crowd during an anti-government protest at Taksim Square, on May 31, 2013. (Reuters/Osman Orsal) #

Demonstrators flee from a water cannon during clashes with riot police, on May 31, 2013 during a protest in Taksim Square in Istanbul. (AFP/Getty Images) #

A Turkish riot policeman uses tear gas as a demonstrator holds a banner which reads, "Chemical Tayyip", referring to Prime Minister Tayyip Erdogan, during a protest in Taksim Square, on May 31, 2013. (Reuters/Murad Sezer) #

Riot police use tear gas to disperse the crowd during an anti-government protest at Taksim Square, Istanbul, on May 31, 2013. (Reuters/Osman Orsal) #

A demonstrator throws a tear gas canister back toward riot police during an anti-government protest in central Istanbul, on May 31, 2013. (Reuters/Murad Sezer) #

A demonstrator reacts as riot police use a water cannon and tear gas to disperse the crowd in Taksim Square, on May 31, 2013. (Reuters/Murad Sezer) #

Riot police fire tear gas canisters in Taksim Square, on May 31, 2013. (Reuters/Murad Sezer) #

A man plants a tree in Istiklal street on June 1, 2013, during a protest against the demolition of Taksim Gezi Park in Istanbul. (Ozan Kose/AFP/Getty Images) #

Protesters arrive in Taksim Square on June 1, 2013 after clashing with riot police in Istanbul. (Bulent Kilic/AFP/Getty Images) #

Supporters of Turkey's Communist Party (TKP) shout slogans during an anti-government protest at Taksim square, on June 1, 2013. (Reuters/Murad Sezer) #

A police officer fires tear gas toward protesters in Taksim Square in Istanbul, on June 1, 2013. (AP Photo) #

Tear gas spreads among demonstrators in Taksim square, on June 1, 2013. (Reuters/Murad Sezer) #

A woman opens her arms as police use a water cannon to disperse protesters on June 1, 2013 during a protest in Istanbul. (Fatih Kece/AFP/Getty Images) #

Tear gas surrounds a protester holding a Turkish flag with a portrait of the founder of modern Turkey Mustafa Kemal Ataturk as he takes part in a demonstration in support of protests in Istanbul and against the Turkish Prime Minister and his ruling Justice and Development Party, in Ankara, on June 1, 2013. (Adem Altan/AFP/Getty Images) #

A woman runs past riot police hiding behind their shields during clashes with demonstrators protesting against Turkey's Prime Minister Tayyip Erdogan and his ruling Justice and Development Party in central Ankara, on June 1, 2013. (Reuters/Umit Bektas) #

Riot police and security men confront protesters at the city's main Taksim Square, on June 1, 2013. (AP Photo) #

Riot police use tear gas to disperse a crowd during an anti-government protest in Istanbul, on June 1, 2013. (Reuters/Murad Sezer) #

A man is struck by a jet of water as riot police use a water cannon to disperse demonstrators during a protest against Turkey's Prime Minister Tayyip Erdogan in central Ankara, on June 1, 2013. (Reuters/Umit Bektas) #

Riot police help a woman affected by tear gas fired during clashes with demonstrators in Ankara, on June 1, 2013. (Reuters/Umit Bektas) #

An injured riot police officer is carried to an ambulance during clashes with demonstrators in Ankara, on June 1, 2013. (Reuters/Umit Bektas) #

Riot police behind shields fire tear gas as they clash with anti-government protesters in Taksim square, on June 1, 2013. (Reuters/Murad Sezer) #

A bleeding protester is assisted as demonstrators clash with riot police on June 1, 2013, in Istanbul. (Bulent Kilic/AFP/Getty Images) #

A security officer in Istanbul's Taksim Square on June 1, 2013. (AP Photo) #

An injured demonstrator is carried to an ambulance during clashes with riot police in Ankara, on June 1, 2013. (Reuters/Umit Bektas) #

An injured man is helped as Turkish protesters clash with riot police near the former Ottoman palace, Dolmabahce, where Turkey's Prime Minister Erdogan maintains an office in Istanbul, late Saturday, June 1, 2013. (AP Photo) #

Turkish protesters confront riot police near the former Ottoman palace, Dolmabahce, in Istanbul, on June 1, 2013. (AP Photo) #

Riot police spray a water cannon at Turkish protesters near the former Ottoman palace, Dolmabahce, in Istanbul, on June 1, 2013. (AP Photo) #

Protesters clash with riot police between Taksim and Besiktas in Istanbul, late on June 1, 2013. (Bulent Kilic/AFP/Getty Images) #

A street vendor sells umbrellas in front of destroyed police cars in Taskim square in Istanbul, early on Sunday, June 2, 2013. (AP Photo/Thanassis Stavrakis) #