The Ecuadorian government declared a state of emergency in two Amazon provinces of Sucumbios and Orellana after protesters caused severe disruption to the country's oil production to press their demand for greater spending on infrastructure and social programs.
The government "has an obligation to protect oil installations, the airports and has to guarantee public security," Interior Minister Mauricio Gandara said after declaring the state of emergency.
The measure triggered a violent reaction in Lago Agrio, 180 km northeast of Quito.
Local television broadcasted footage of residents attacking a municipal building, smashing windows and looting computers, books and other office supplies.
Residents of the two Amazon provinces in Ecuador's northeast Amazon obstructed the main roads leading to oil fields in the zone since Sunday morning, and the protests also shut down operations at two provincial airports.
Some 3,000 soldiers and police were in the zone to force out protesters who had taken over about 250 wells, authorities said.
Officials at state-run oil company Petroecuador said crude oil production had dropped 90 percent from 202,500 barrels to 20,000 barrels, causing losses of about 12 million US dollars in revenue from Monday to Wednesday.