Supporters clashed with bailiffs and riot police at the UK's largest illegal travellers' site as the planned eviction finally got under way.
Bricks were thrown at police as they stormed barricades at Dale Farm, near Basildon in Essex.
Many of those trying to stop the eviction wore scarves to cover their faces.
Travellers and supporters inside Dale Farm had locked down the site last night and three people were planning to chain themselves to the main gate by the neck.
Supporters quickly erected barricades inside the site as police held the line, securing the rear area.
Electricity supplies have been cut. Supporters say this has turned off crucial medical equipment belonging to elderly residents.
Supporters chanted: "F*** the police, no justice, no peace."
Several supporters have been detained after violent clashes.
Essex Police said two protesters have been Tasered and one person arrested. They made a number of attempts to negotiate with demonstrators to leave the site peacefully.
The force said: "Intelligence received indicated protesters had stockpiled various items with the intent of using these against bailiffs and police.
"The first officers on the site were attacked with missiles being thrown, including rocks and liquids. These officers were fully equipped to deal with this situation."
Paramedics have been escorted on to the site by supporters to treat resident Nora Egan, who claims she suffered back injuries in a confrontation with police.
Earlier the leader of Basildon council Tony Ball said no further negotiations would take place.
Mr Ball also condemned the violent scenes today.
He said: "These are utterly disgraceful scenes and demonstrate the fact some so-called supporters were always intent on violence."