Venezuelan security forces quelled masked protesters with tear gas, water cannons and pepper spray in Caracas on Tuesday after blocking an opposition rally against socialist President Nicolas Maduro.

The clashes began after authorities closed subway stations, set up checkpoints and cordoned off a square where opponents had planned their latest protest against autocratic government and a crippling economic crisis.

In cat-and-mouse skirmishes on backstreets and highways around the capital, youths built barricades, burned trash and hurled rocks and bottles at soldiers and police. Various opposition leaders organized roadblocks.

Police used pepper spray on National Assembly head Julio Borges, two-time presidential candidate Henrique Capriles and rights activist Lilian Tintori, as they led protesters onto highways and jostled at barricades, witnesses said.

Opposition activists said armed pro-government gangs joined the fray and opened fire. "About 50-100 guys arrived on bike and started to shoot in the air," protester Bernardo Sanchez told local media, saying a bullet had lodged in his thigh.

In one street, kneeling women sang the national anthem as neighbors banged pots and pans from nearby buildings in a show of anger against a government they blame for a deep recession that has led to shortages of food and basics.

"We're going to get rid of them but we have to fight," said Jose Zapata, 57, an electrician, as he marched with a stick in his hand. Overlooking one wide avenue, some pro-Maduro residents in a state housing project threw trash onto protesters below.

With thousands out on both sides, supporters of the 54-year-old president organized their own rally, in a volatile scenario seen constantly during the 18 years of leftist rule in the South American nation.

"They want an intervention in Venezuela," said Prisons Ministry worker Juan Aponte, 34, who wore the red colors of the ruling Socialist Party. Protests also were staged in other cities and more are planned across the country for Thursday.

The government accuses opposition parties of abetting a U.S.-led plot to topple Maduro, who has ruled Venezuela since the 2013 death of Hugo Chavez.