At least 18 people have been killed and dozens wounded across Myanmar in the most violent crackdown yet by security forces against peaceful demonstrators protesting against a February 1 military coup.

The violence erupted early on Sunday morning when medical students were marching in Myanmar’s largest city Yangon’s streets near the Hledan Center intersection. Police fired tear gas and water cannons where the anti-coup protest was underway with scores of students and other demonstrators hauled away in police trucks.

 Protesters were seen running away from the police as they charged at them, and residents were setting up makeshift roadblocks to slow their advance. Nearby, residents were pleading with police to release those they picked up from the street and shoved into police trucks to be taken away. Nearly 800 people have been reportedly arrested since the coup.

Myanmar’s crisis took a dramatic turn on the international stage over the weekend at a special session of the United Nations General Assembly when the country’s UN ambassador declared his loyalty to the ousted civilian government of Aung San Suu Kyi and called on the world to pressure the military to cede power.