Protesters intent on driving out Venezuela’s embattled president took back to the streets on Tuesday, calling upon soldiers to join them in a national uprising.

The demonstrations in Caracas, the capital, soon turned violent, as protesters and law enforcement officers loyal to President Nicolás Maduro clashed.

Tensions began building after the Venezuelan opposition leader, Juan Guaidó, stepped up his campaign to oust Mr. Maduro.

Mr. Guaidó, who declared himself interim president in January, showed up at a military base in the capital and, accompanied by a few soldiers, declared that “the definitive end of the usurpation starts today.”