Fighting between the Myanmar junta and rebels scaled up on Saturday in Myawaddy, a town close to the Thai border.
That’s according to witnesses, media and Thailand’s government.
Rebels were pressed to flush out junta troops holed up for days at a bridge border crossing.
While a helicopter appeared to get hit, thick black smoke was seen rising.
Several Thai media outlets said about 200 civilians had crossed the border to seek temporary refuge in Thailand.
Resistance fighters and ethnic minority rebels seized the key trading town of Myawaddy on the Myanmar side of the frontier on April 11.
It was a big blow to a well-equipped military that is struggling to govern and is now facing a critical test of its battlefield credibility.
They targeted an estimated 200 junta soldiers who had retreated from a coordinated rebel assault on Myawaddy and army posts since April 5.
Thai Prime Minister Srettha Thavisin said he was monitoring the unrest and Thailand was ready to provide humanitarian assistance if necessary.
Myanmar’s military took control in 2021 from an elected government led by Aung San Suu Kyi, who remains in detention.
The country is locked in a civil war between the military on one side and, on the other, a loose alliance of established ethnic minority armies and a resistance movement born out of the junta’s bloody crackdown on anti-coup protests.