The explosion killed five people and injured 35 others at a café in the town of Adi-Da'ero, according to officials in Ethiopia's Tigray region.
The blast occurred at around 4:30 p.m. on Saturday, destroying the café and a nearby house. Local security officials secured the area immediately and rushed victims of the attack to a nearby hospital.
"I visited the victims who were admitted to the zonal hospital," said Michale Abraha, the administrator of the northwestern zone of Tigray. "Some 15 of them suffered minor injuries, so they are sent home after receiving medical care. Five are heavily wounded but under stable conditions."
The dead include three men, a woman and a seven-year-old girl.
Regional officials blamed the Eritrean government for the attacks. "We know agents of the Eritrean government carried out the attack," Michale said. "The Eritrean government has been engaged in activities to destabilize Ethiopia and is planning to disrupt the democratic election in Ethiopia."
Despite repeated efforts to contact Eritrean government, officials were unavailable for comment.