According to a statement issued by the Directorate of Presidential Communications, President Kikwete said that he received the news with great shock and immense sorrow.
"Once again we witness the loss of innocent brothers and sisters who continue to perish in road accidents that keep recurring. We earnestly need the wisdom and integrity of drivers to abide by road safety regulations to avoid such accidents," he said.
The accident involved the passenger bus, christened Sabena which was on its way to Mbeya from Tabora. The bus reportedly had more than 100 passengers on board.
Meanwhile, Gloria Tesha reports from Accra that President Kikwete is among 16 heads of state and government scheduled to attend the burial of former Ghanaian President John Atta -Mills here today.
Mr Kikwete and his wife Mama Salma Kikwete are expected here today. Thousands of mourners have been paying their last respects to the departed leader who died on July 24, of throat cancer.
US Secretary of State Hillary Clinton is also expected to attend the burial ceremony. The Chairperson of the funeral committee, Mr Koffi Totobi-Quakyi, said the late Atta-Mills, the first Ghanaian president to die in office, is to be buried on the grounds of the seat of government at Osu Castle in Accra.
The capital has been filled with tributes to Mills, who was widely praised for his integrity, including billboards, saying "we shall always remember you," while some could be seen wearing black and red bands and scarves as symbols of grief.
"The outpourings of emotions on the death of our president show that we Ghanaians are united in our collective sense of loss," Totobi-Quakyie said.
Accra police commissioner Patrick Timbillah said heavy security would be in place for the funeral, with major roads cordoned off. Totobi-Quakyi said the family will hold a private service in Mills' place of birth on Sunday in the village of Ekumfi Otuam.