Thousands of people flocked to Guatemala City's main plaza on Saturday in the biggest protest yet against President Alejandro Giammattei's government - over cuts in the 2021 budget - with some setting fire to the Congress building.

Waving national flags and signs declaring "Giammattei, resign," demonstrators called for Giammattei to veto the budget, which lawmakers approved at dawn last Wednesday even as Hurricane Iota was drenching parts of the Central American country still reeling from the destruction of a prior storm. 

At 99.7 billion quetzals (about $12.9 billion), the budget increased public debt while cutting funding for healthcare, education, human rights and the justice system, outraging people from students to business leaders in a year marked by the economic crisis of the coronavirus pandemic.

"Congress allocated more money for their meals and didn't allocate money to the poor people," said Diego Herrera, 25, a student.

While most protesters assembled peacefully at the main square, others set part of the historic Congress building on fire, sending up dramatic orange flames and a cloud of smoke that could be seen blocks away.

A spokeswoman for San Juan de Dios General Hospital, one of the capital city's biggest hospitals, said it was treating 14 people for multiple injuries and tear gas poisoning after protesters clashed with police in riot gear who used tear gas to disperse the crowds.

Giammattei told national television on Friday he would meet with "whomever necessary" to explain the budget. As protests ramped up Saturday, he said on Twitter he was meeting with various sectors to analyze modifications to the budget. He did not provide details.

Vice President Guillermo Castillo opposed the budget plan and has suggested both men resign.

Giammattei took office in January, shortly before the COVID-19 pandemic, forcing lockdown measures that crimped the already weak economy. In November, two fierce hurricanes - Eta followed just two weeks later by Iota - killed 60 people, with many more missing, and destroyed crops that had sustained tens of thousands of families.