Thu Sep 27, 5:45 AM ET

YANGON - Thousands of protesters emptied the streets of central Yangon on Thursday after Myanmar's soldiers issued an ultimatum threatening "extreme action" unless the crowd dispersed, witnesses said.

Pockets of people remained on balconies and bridges, as soldiers and police worked systematically through the city centre to ensure that no protesters remained.

At least 100 people were arrested and thrown into military trucks after the ultimatum. Security forces had earlier fired warning shots, but the crowd only broke up after soldiers issued their warning.