A volunteer ambulance driver was killed and several others sustained injuries during a clash that broke between separatist rebels and government forces in northern Myanmar last week.
The rescue workers were about 20 kilometres from Lashio, the largest town in Shan State, where armed groups have been fighting for greater autonomy from the central government when their convoy came under attack on Saturday, Al Jazeera reported.
The area around Lashio is also home to what is believed to be the world's largest methamphetamine-producing region.
Tensions in the region have risen since last Thursday, when the Northern Alliance rebels staged attacks, including on an elite army college that killed more than a dozen people, mostly security forces personnel.
Army spokesman Tun Tun Nyi said rebels attacked a petrol station and a bridge in another location on Saturday morning, and rescue workers were travelling there when they were attacked.
The Myanmar army said this weeks' attacks were retaliation for a large drug seizure made in July.
Myanmar's civilian leader Aung San Suu Kyi came to power following a landslide election win in late 2016, vowing to prioritise peace talks between ethnic armed groups, the military and civilian government.
But the conflict has escalated in northern Kachin and Shan states as well as the western Rakhine region on the border with Bangladesh.
( With inputs from ANI )