Three blasts hit the city of Maiduguri in northeast Nigeria on Tuesday killing a number of people, locals and the Red Cross said.
The "huge explosions" happened in the Ajilari Cross area of the city, which has been targeted by similar attacks twice in the last month, including on September 20 when at least 117 were killed.
The previous attacks were blamed on Boko Haram Islamists, which has increasingly hit "soft" civilian targets in recent months using suicide bombers and improvised explosive devices.
It was not immediately clear what caused the latest blasts, which happened in quick succession from 8:10 pm (1910 GMT), said Bashir Mohammed, whose house is near the scene.
"We are all confused and people are running helter-skelter," he said.
Sheriff Ahmad, a cleric in the area, said: "Many people have been killed. I don't know how many and I don't think anyone can tell you now."
Ahmad described seeing body parts on his house, while Hafsat Sani, a nurse at the nearby Umaru Shehu Hospital, said: "There are many houses around the area and the blasts have affected many of them."
The hospital quickly began receiving the injured while police, soldiers, the Red Cross and officials from Nigeria's National Emergency Management Agency (NEMA) were mobilised, he said.
A Red Cross official said: "Obviously there are people that died but I don't have figures."
There was no immediate comment from the police or military while details were sketchy as Maiduguri is subject to a night-time curfew.
On October 1, at least 10 people were killed and 39 injured when four suicide bombers blew themselves up in a wave of attacks in Ajilari Cross, which is near Maidugiri airport and a military base.
At least two bombs were strapped to teenage girls, witnesses and the police said at the time.
The September 20 attack targeted a mosque and killed football fans watching a televised match as well as bystanders.
- Abuja arrests -
Amnesty International said last month that the Boko Haram conflict had killed at least 1,600 people since the start of June in Nigeria, Niger, Chad and Cameroon and called for more protection for civilians.
An AFP tally puts the death toll at more than 1,320 in Nigeria alone since Muhammadu Buhari became president on May 29.
Boko Haram claimed responsibility for three suicide attacks in the satellite towns of Kuje and Nyanya outside Nigeria's capital Abuja on October 2, which killed a total of 18 people and injured 41.
On Tuesday, Nigeria's most senior police officer, Inspector General of Police Solomon Arase, said two people had been arrested on suspicion of masterminding the blasts.
The suspects' identities were not disclosed but Arase said in a statement the arrests had "foiled another attempt... to undertake further attacks in the FCT (Federal Capital Territory)".
Items recovered from the suspects included 12 "prepared and primed" home-made explosives concealed in soft drink cans, 28 electronic detonator parts and a "large quantity" of bomb-making equipment, he added.
Nigeria's military has claimed a series of successes in recent months and has characterised the upsurge in attacks on civilian targets as desperation on the part of the Islamic State group-alled militants.
Attacks have also continued across the border. At the weekend, 41 people were killed and another 48 injured in triple explosions in Baga Sola, on the Chadian side of Lake Chad, where Nigeria meets Niger, Chad and Cameroon.
One targeted a fish market and two a refugee camp for those displaced by the violence.