Myanmar security forces backed by armored vehicles clashed on Tuesday with a newly formed militia group in the second-biggest city of Mandalay, resulting in at least two casualties, according to members of the group and media reports.

Since the army seized power on Feb. 1 and removed the elected government of Aung San Suu Kyi, the security forces have put down protests opposing military rule. In response, groups of opponents of the coup known as people's defense forces have sprung up across Myanmar.

Up to now, fighting involving lightly armed militias has been mainly confined to small towns and rural areas, but a group claiming to be Mandalay's new People's Defence Force said its members responded after the army raided one of its bases.