PARIS — French activists fired a flare at a police helicopter and clashed with riot officers Tuesday in western France as authorities cleared out a protest camp erected nearly a decade ago to block construction of an airport.

Eleven police officers were injured and 16 squats were dismantled on the second day of the government's evacuation operation at the site of Notre-Dame-des-Landes, said the head of the regional administration, Nicole Klein.

The clashes come at a time of simmering public protest in France, including nationwide train strikes, an Air France workers' strike and blockades by students at public universities.

Authorities said about 350 people are resisting the authorities' evacuation operation at Notre-Dame-des-Landes.

The national gendarme service said an investigation is underway into the flare launched at the helicopter flying over the area Tuesday.

Activists also clashed with riot police when the evacuation began Monday, and one officer was hospitalized after being hit in the eye with a flare.

French President Emmanuel Macron's government in January abandoned plans for the airport, near the city of Nantes, after 50 years of debate, and gave squatters until spring to clear out. The government requisitioned the land from farmers for the airport, but is now offering to return the land to those who want it.

Proponents had argued the region needed a larger airport to boost its economic prospects. Opponents said a new airport was unnecessary and a symbol of exploitative globalization.