On Monday a French climber died and four people were injured after the massive ice pinnacle  -- known as a serac -- fell.
The two German climbers, both in their 30s, were declared missing.
Rescue services found an ice pick on the edge of a crevasse, which led investigators to believe that they had been swept away by an avalanche triggered by the toppling ice block, said Jean Ailhaud, deputy prosecutor in the Alpine town of Bonneville.
It was too risky for search teams to descend into the crevasse because of the snow that had piled up there, he told AFP.
A search was called off Monday because of the vast size of the accident site and the risk of more avalanches.
The two Germans had sheltered for the night in a mountain hut on the north face of the Mont Blanc, western Europe's highest mountain, when the serac broke off the glacier in the early hours of Monday at an altitude of 4,100 metres.
READ MORE: Why is climbing Mont Blanc so dangerous?
Around 15 people were ascending the mountain at the time.
A rescue team with helicopters and search dogs searched for survivors. They found the body of a 57-year-old Frenchman. A man and woman in their 40s, also French, were taken to hospital.
A 58-year-old Spanish national and his teenage son suffered fractures when they were hit by falling ice.
All other climbers present at the time of the accident were accounted for, except the two Germans, emergency services said.
Climate change has been blamed for falling rocks in the French Alps because the permafrost -- the year-round ice found at high altitude that binds together giant slabs of rock.
Retreating glaciers, which are melting under the effect of higher temperatures, are also leaving the peaks more vulnerable.
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