Venezuelan soldiers opened fire on civilians at the Brazil border Friday morning.

It was the most violent clash so far in a mass effort to bring international aid into the country.

Venezuelan President Nicolás Maduro announced Thursday he'd close his country's border with Brazil to stop opposition from bringing in humanitarian aid.

Maduro  previously blocked a bridge  connecting Venezuela and Colombia with both physical barriers and security forces.

Opposition leader Juan Guaidó called for the foreign aid last month.

Venezuela is facing a huge  economic and political crisis .

Since 2014, around 2.5 million people have reportedly fled the country due to food shortages and massive inflation, among other problems. The Venezuela-Brazil border was set to officially close Friday morning, and indigenous demonstrators showed up to block military vehicles.

Soldiers responded by firing assault rifles at the civilians.

At least one person died and around a dozen were wounded.

At the Venezuela-Colombia border on Thursday, opposition supporters forcefully drove trucks through security forces to pick up supplies waiting for them in Colombia.

Soldiers fired tear gas, but the trucks made it through.

On Saturday morning, exactly one month after Guaidó declared himself interim president, the opposition is calling for thousands of people to help bring supplies into Venezuela.

U.S. Vice President Mike Pence is scheduled to give a speech in Colombia next week regarding Venezuela's humanitarian crisis.

Additional reporting from  Newsy affiliate CNN .