The number of people killed by cholera in Tanzania's commercial capital Dar es Salaam rose from one to four on Monday, Xinhua reported.
Kinondoni municipal health authorities said the number of patients admitted to hospitals increased from six as of Monday.
However, the medical authorities said they were trying to establish the source of the outbreak the deadly disease.
Musa Naty, the Kinondoni municipal director, confirmed that four patients were diagnosed with cholera after samples of their stools tested positive for the bacterial infection.
"They will be transferred to a special treatment camp located in Mburahati ward," said Naty.
He said public health authorities have embarked on preventive measures to contain the deadly waterborne disease.
Naty said that a team of health workers had started fumigating some of the hotspot areas in Kinondoni municipal.
"We want to ensure that we control the epidemic before it spreads further. We are treating the patients with symptoms of the disease but the aim is to prevent it," he said.
Two isolation wards have been established at Sinza and Mwananyamala Hospitals as reports of new patients continued to be recorded.