Updated

Rescue teams in South Africa have asked the military to help find a 5-year-old boy who fell into a disused mine shaft last weekend.

Military officials arrived at the scene Thursday after fruitless efforts to locate Richard Thole, who disappeared into the shaft while playing Saturday near his home in Boksburg, near Johannesburg.

Emergency responders say the shaft is 140 meters (460 feet) deep and contains potentially lethal gas as well as acidic water. An underground fall of rocks on Wednesday further hampered the search.

The area where the boy fell is known as Jerusalem, with makeshift homes constructed over old gold mines. Authorities say it is unsafe and that the residents should move. One resident, Zodwa Mashabane, says the ground under her home is sinking.