The bomb exploded in the Macampagne market in Beni where "at least 17 people were wounded and were taken to medical facilities," said Tharcisse Katembo, head of the blue-collar district.
An AFP correspondent saw at least eight wounded, including three girls, being treated at the clinic.
The victims suffered injuries to their feet, arms and heads, the correspondent said.
"A young man left a green plastic bag... promising to come back and get it. About three minutes later, the bag exploded, injuring people including myself and the customers who had come to grind their cassava," Dany Siauswa, manager of a mill business, told AFP.
Joseph Kakule, a local civil society leader, said "at least 19 people were injured" because of the shrapnel.
Beni region is one of the most volatile areas in the east of the DRC, which has been plagued by insecurity for nearly 30 years.
On Jan. 15, an attack blamed on the Allied Democratic Forces (ADF), a group affiliated with Islamic State group jihadists, killed around 15 people in an evangelical Protestant church in Kasindi, on the border with Uganda.
The militia is accused of killing at least 23 villagers on Monday. The attack was claimed by the Islamic State group.
A joint Congolese-Ugandan military operation targeting the ADF in the region has been underway since late 2021. But the attacks continue.