Police is requested people to abstain from visiting the Salawa Army Camp in Kosgama, Avissawella.
Heavy traffic is reported in the area as people arrive to see the explosion, police said.
The number of injured during the explosion has reached 47.
A Bell 212 helicopter of the Sri Lanka Air Force was deployed this morning to inspect the area, Army Media Spokesperson Brigadier Jayanath Jayaweera said.
Security forces say that residents living one kilometer away from the Salawa Army Camp can return to their houses.
Army has warned people to refrain from touching any objects lying around in the area as there is a risk of explosions.
In case such materials are found contact the army headquarters be contacted via hot line 011 3 81 86 09 or 011 2 43 42 51.
Meanwhile, Director General of Health Services Dr. Palitha Mahipala warned the people to avoid drinking water from wells in the area. He said that toxic materials could mix with the water during the explosion.