At least 30 people were killed in the north-east Nigerian state of Borno after an improvised explosive device detonated on a bridge.
The bomb detonated at roughly 5 pm local time on Monday on a crowded bridge in the market town of Gamboru that leads into neighbouring Cameroon.
Witnesses in the market town said more than 35 injured people were taken to the local hospital following the attack.
"It is an unfortunate day for us to witness this frustrating and devastating incident in our community," eyewitness Modu Ali Said told Reuters.
"I just heard a loud sound of explosions, before I realized I saw many of our friends and colleagues were killed," Said added.
Two sources with the Civilian Joint Task Force, a group of citizens formed to fight Boko Haram, confirmed the attack and the early death toll estimates.
No group immediately took responsibility. Both Boko Haram and the regional offshoot of ISIS, known as ISWAP, are active in the area.
Militant groups have targeted Gamboru numerous times since 2014 when Boko Haram seized the town and nearby Ngala.
But, the Nigerian military were able to recapture the city after a long siege with the help of soldiers from Chad.
The Boko Haram insurgency has killed more than 35,000 people and displaced more than 2 million in the area.
Seperatly on Tuesday, Nigerian media reported that three men were killed in a Boko Haram attack on a village in the Chibok region. The militants reportedly looted homes and set fire to buildings.
In 2014, Boko Haram kidnapped 276 female students from a secondary school in the Chibok area sparking an international effort to free the girls.