The explosion took place around 7 am while ammunition was being unloaded for disposal, a Defence official said.
Around 10 to 15 contract labourers were at the site when the incident occurred, Wardha’s Additional Superintendent of Police Nikhil Pingle said.
“The blast occurred in one of the ammunition boxes while unloading the ammunition. The incident took place in an open land,” he said.
While four people were killed on the spot, two others succumbed to injuries in hospital, Inspector General of Police (Nagpur Range) K M M Prasanna told PTI.
The deceased included an ammunition factory employee and labourers.
The injured were admitted to a hospital in the nearby Savangi village, another police official said.
Police and fire brigade officials rushed to the spot to carry out the rescue operation.
The demolition ground at the Central Ammunition Depot at Pulgaon in the district was given to the Ammunition Factory, Khamaria (Madhya Pradesh), for demolition activities, he said.
In 2016, 16 people were killed in a blast at the ammunition depot at Pulgaon in 2016.