"It started when a group of farmers took some cows, claiming that they had destroyed their crops," local police chief Faustine Shilogile said, from the central Morogoro region.
"The herders came to take their cattle back by force and clashes broke out... Six people were killed."
Conflicts between farmers and herders are common in Tanzania, notably in the region of Morogoro, where the land is particularly fertile.
Police had since restored calm to the area, Shilogile added.