Sayed Mehraj Sadat, the police chief in Takhar province, said the bomb's intended target was most likely Afghan security forces, who often use the road the children were walking on. No one immediately claimed responsibility for the attack.
Sadat said the victims were between 10 and 15 years old. Provincial police spokesman Khalil Asir told Reuters the victims were between the ages of nine and 12 and included four children from a "Taliban family." The discrepancy could not immediately be reconciled.
In October, the Taliban launched large-scale attacks in several districts, including the provincial capital Taluqan, which were repelled by Afghan security forces.
"This area is under Taliban control and since security forces launched attacks to clear it, the Taliban have planted anti-personnel mines," Asir told Reuters.
According to the United Nations, 1,174 Afghan civilians were killed between July and September in the country's decades-long war, according to the United Nations. More than 3,000 were injured over the same time period, a 42 percent increase over the year before.
"Civilian casualties at record-high levels clearly show the need for all parties concerned to pay much more attention to protecting the civilian population, including through a review of conduct during combat operations," said Tadamichi Yamamoto, the U.N. secretary-general's special representative for Afghanistan.
In May, a landmine killed seven children in the southern province of Ghazni. And in February, seven children were killed in Laghman province when a mortar shell the children were playing with exploded.
On Oct. 18, at least 62 people were killed after a bomb went off causing the roof of a mosque to cave in during Friday prayers in Nangarhar province.
In September, President Trump tweeted that the Taliban “has never been hit harder than it is being hit right now,” after year-peace talks between the U.S. and the Taliban abruptly ended.
The Associated Press contributed to this report.