The quake, of magnitude 5.9, occurred on Saturday morning 27 kilometers east of the Rasht district.
Tremors were also felt in the capital, about 165 kilometers southwest of the epicenter.
According to the Tajik committee for emergency situations, dozens of houses were destroyed, and power lines were also partially damaged in three villages in Tajikabad district, where all the victims lived.
The earthquake occurred at 07:14 local time and at a depth of 10 kilometers, according to the committee and the state news agency Khovar.
Tajik President Emomali Rakhmon appointed a commission headed by Prime Minister Kokhir Rasulzoda to assess the damage and subsequently offer financial assistance.