May Day clashes between opposition supporters and Venezuela’s armed forces in Caracas left a woman dead and 46 people injured on Wednesday, with opposition leader Juan Guaido attempting to rally demonstrators against President Nicolas Maduro.

Jurubith Rausseo, 27, died at a clinic after being hit by a “bullet in the head during a demonstration,” the non-governmental Venezuelan Observatory of Social Conflict said on Twitter, condemning her “murder.”

Human rights organizations and health services reported 46 people injured in Wednesday’s clashes, including one person with a gunshot wound.

Tensions in Venezuela have soared since Guaido, who heads the National Assembly legislature, invoked the constitution to declare himself acting president on January 23, claiming Maduro’s re-election last year was illegitimate.

National Guard troops fired tear gas at stone-throwing protesters attempting to block a highway close to the air base in eastern Caracas where Guaido had tried on Tuesday to spark a military uprising.

A second day of confrontations between opposition supporters and Maduro’s security services came as the United States said it was prepared to take military action, if necessary, to stem the crisis in the South American nation.

At least one journalist was injured when National Guard soldiers fired rubber bullets at a group of reporters covering the clashes.

Miguel Ramirez, 17, told AFP at one medical center that he had been shot in the foot while protesting on the highway near the La Carlota air base.

“I didn’t manage to run and hide,” he said.

Guaido rallied his supporters in Caracas in the Labor Day demonstrations, urging them to stay in the streets.

His appeal came despite the apparent failure the day before of a revolt by some soldiers and members of the Bolivarian National Guard who joined his side.

In Tuesday’s clashes, one person was killed and dozens injured, according to human rights monitors. More than 150 people were arrested, the government and human rights organizations said.

UN Secretary General Antonio Guterres warned Venezuela’s authorities not to use deadly force against demonstrators, while the US and Russia accused each other of making the crisis worse, evoking Cold War confrontations of the past.

In a phone call with Russian Foreign Minister Sergei Lavrov, US Secretary of State Mike Pompeo accused Moscow of “destabilizing” Venezuela.