Myanmar police fired rubber bullets to disperse protesters in Yangon on Saturday, according to an AFP reporter, after the country's ambassador to the United Nations broke ranks to make an emotional plea for action against the military junta.
The country has been shaken by a wave of pro-democracy protests since a military coup toppled civilian leader Aung San Suu Kyi on February 1.
It was unclear if any live rounds were used as police chased protesters and journalists from the Myaynigone junction.
There had been an hours-long standoff on Friday at the same spot.
Hundreds of ethnic Mon protesters gathered there on Saturday to commemorate Mon National Day, joined by other ethnic minority groups to protest against the coup.
The police arrived to clear the intersection, chasing protesters and journalists who ran to hide in nearby buildings.
Three journalists were among those detained on Saturday.
"What are the police doing? They are protecting a crazy dictator," the protesters chanted.
They scattered into smaller residential streets and started building makeshift barricades out of barbed wire and tables to stop the police.
Local reporters broadcast the chaotic scenes live on Facebook, including the moments when the shots rang out.
"We will try to find another way to protest -- of course, we are afraid of their crackdown," said protester Moe Moe, 23, who used a pseudonym.
"We want to fight until we win."