Venezuela’s National Guard fired tear gas at protesters clearing a barricaded border bridge between Venezuela and Colombia on Saturday, heightening tensions over blocked humanitarian aid that opposition leader Juan Guaido has vowed to bring into the country despite objections from President Nicolas Maduro.

Throughout the turbulent day, as police and protesters squared off two bridges connecting Venezuela to Colombia, Guaido made repeated calls for the military to join him in the fight against Maduro’s “dictatorship”.

Colombian authorities said more than 60 soldiers answered his call, deserting their posts in often gripping fashion, though most were lower in rank and didn’t appear to dent the higher command’s continued loyalty to Maduro’s socialist government.

In one dramatic high point, a group of activists led by exiled legislators managed to escort three flatbed trucks of aid past the halfway point into Venezuela when they were repelled by security forces.

In a flash, the cargo caught fire, with some witnesses claiming the troops doused a tarp covering the boxes with gas before setting it on fire.

During a speech in front of a crowd of thousands on Saturday at an outdoor rally in Caracas, Maduro slammed those attempting to bring food and medical supplies into the country as “traitors”.