The army takeover and arrest of elected leader Aung San Suu Kyi has plunged Myanmar into chaos. Security forces have killed over 60 protesters and detained more than 1,800 since then, an advocacy group said.
In Sanchaung, police firing guns and using stun grenades announced on Monday they would check houses for anyone from outside the district and would punish anyone caught hiding them.
U.N. Secretary-General Antonio Guterres had earlier called for "maximum restraint" and the safe release of all protesters without violence or arrests, a call echoed by the U.S. and British embassies in Myanmar.
An advocacy rights group said around 50 people had been arrested in Sanchaung after police searched houses, though checks were still being made.
A junta spokesman did not answer calls requesting comment.