Myanmar security forces on Thursday arrested Paing Takhon, a model and actor who had spoken out against the coup, his sister told Reuters, as activists placed shoes filled with flowers in parts of Yangon to commemorate dead protesters.
Troops opened fire on pro-democracy protesters on Wednesday, killing at least 15 people and wounding dozens, activists and media said.
Nearly 600 civilians have been killed by security forces in the turmoil since the junta seized power from the elected government of Aung San Su Kyi in February, the Assistance Association for Political Prisoners (AAPP) said on Wednesday.
The advocacy group said 2,847 were currently being held in detention.
A spokesman for the junta could not be reached for comment.
Arrest warrants have been issued for hundreds of people, with the junta this week going after scores of influencers, entertainers, artists and musicians.