At least 18 people were killed and dozens of others were injured in a series of suicide bombings, all carried out by women, on Saturday afternoon in northeastern Nigeria.They included one explosion that went off at the wedding of a young couple and another at a funeral, according to local officials.

Barkindo Saidu, the director general of Borno State’s emergency management agency, said that three female attackers had struck distinct locations in Gwoza, a bustling city in Borno State that has been the center of an insurgency by the militant group Boko Haram over the last 15 years.

The victims included children and pregnant women, Mr. Saidu said. Some Nigerian news outlets reported that at least 30 people had been killed.

As of Sunday afternoon, no group had claimed responsibility for the bombings. The blasts resembled attacks carried out by Boko Haram, whose fighters have killed tens of thousands in Nigeria and whose aggression in the region has led to the displacement of more than two million people.

The number of suicide bombings has decreased in recent years, but Saturday’s multiple blasts were a reminder that terrorism remains a vivid threat in northeastern Nigeria.

The first attacker on Saturday detonated a bomb that she was wearing at a wedding celebration, Mr. Saidu said in a preliminary report seen by The New York Times. Seven people died in that explosion, including the attacker and a baby she had with her, according to Kenneth Daso, a public relations officer with the police in Borno.