"This disaster has cost 76 lives in Katesh area, up to this afternoon," Hassan said, revising upwards an earlier toll from last week's disaster in the hillside town of Katesh, 300 kilometers north of the capital Dodoma.
Torrential downpours over the weekend washed away vehicles, brought down buildings, and destroyed infrastructure in many parts of the country.
Hassan said, "the disaster is also a wake-up call for the government to make necessary preparedness to detect the signs and alert people in advance so that we avoid serious effect like this."
She promised that the state would help with recovery efforts.
The East African leader cut short her participation in the COP28 climate talks in Dubai to deal with the disaster.
Images broadcast on television showed debris from houses, including furniture, strewn across streets, with key roads, power lines and communication networks disrupted.
Some 5,600 people have been displaced by the landslides, according to government spokesman Mobhare Matinyi.
Tanzania and its East African neighbors Kenya, Somalia and Ethiopia have all been battling flash floods caused by torrential rains linked to the El Nino weather pattern.
The floods are exacerbating the humanitarian crisis in the region just as it emerges from its worst drought in four decades that left millions hungry.
Between October 1997 and January 1998, widespread flooding caused more than 6,000 deaths across five countries in the region.
Scientists say extreme weather events such as flooding, storms, droughts and wildfires are being made longer, more intense and more frequent by human-induced climate change.