Four persons were killed and five injured on Saturday when a metal container carrying gelatin sticks, attached to a tractor, exploded in Maharashtra’s Yavatmal district, police said.The incident occurred in the Umarkhed area, they said.A tractor, which was being used for blasting work, had been brought to a welding workshop on Dhanaki Road for repairs, said police.When welding work was in progress, a metal container carrying gelatin sticks and attached to the tractor exploded, triggering a fire. An air cylinder near the rear tyre was also found ripped open, they said.Four persons succumbed to burns that they sustained in the accident, while five others were injured, said an official from Umarkhed police station.Locals rushed to the spot after hearing the blast and helped move the injured to Umarkhed Sub-District Hospital. The injured persons were later shifted to another hospital for further treatment.A probe into the incident is under way, police said.