The army said it had carried out the detentions in response to "election fraud", handing power to military chief Min Aung Hlaing and imposing a state of emergency for one year, according to a statement on a military-owned television station. A military spokesman did not answer phone calls seeking further comment.
Phone lines to the capital Naypyitaw and the main commercial centre of Yangon were not reachable, and state TV went off air hours before parliament had been due to sit for the first time since the NLD's landslide election win in November, viewed as a referendum on Suu Kyi's fledgling democratic government.
Soldiers took up positions at city hall in Yangon and mobile internet data and phone services in the NLD stronghold were disrupted, residents said. Internet connectivity also had fallen dramatically, monitoring service NetBlocks said.
Suu Kyi, Myanmar President Win Myint and other NLD leaders had been "taken" in the early hours of the morning, NLD spokesman Myo Nyunt told Reuters by phone.