(Reuters) - At least 13 people including young children were killed when a bomb tore through a venue in northeast Nigeria where fans had gathered to watch a World Cup soccer match, witnesses said.
Some people at the scene told Reuters an attacker dropped a device in front of the venue on Tuesday night in the town of Damaturu and ran off, while others said it was the work of a suicide bomber.
No one claimed responsibility for the blast, but Damaturu and the surrounding Yobe state are at the heart of a five-year-old insurgency by Islamist group Boko Haram.
The group was blamed for a an attack on another venue screening soccer matches in the northeastern state of Adamawa that killed at least 14 people and wounded 12..
A Reuters reporter at Damaturu's General Sani Abacha Specialist Hospital counted 13 people dead - including small children - and at least 20 wounded.
The Nigerian government has advised people to avoid gathering in public to watch the World Cup, concerned about potential attacks.
Many fans in soccer-mad Africa rely on informal venues - often open-sided structures with televisions set up in shops and side streets - to watch live coverage of the sport.
Boko Haram - whose name roughly translates as "Western education is sinful" - has declared war on all signs of what it sees as corrupting Western influence.
The group has killed thousands in its push to carve out an Islamic state in religiously-mixed Nigeria.
(Reporting by Joe Hemba; Writing by David Dolan; Editing by Toby Chopra)
Police Assistant Superintendent Nathan Cheghan confirmed the explosion but said rescue workers were being careful for fear of secondary explosions. Islamic extremists of the Boko Haram group frequently time secondary explosions to kill people who rush to the scene of a bomb blast.
Cheghan said he had no casualty figures.
There was no immediate claim for the blast witnesses were blaming on Boko Haram fighters who have targeted football viewing centers and sports bars in the past. Two explosions in recent weeks killed at least 40 people in two northern cities.
Witnesses said the tricycle taxi was driven into the outdoor area soon after the Brazil-Mexico match started Tuesday night. All spoke on condition of anonymity for fear of reprisals.
One hospital worker said he saw at least seven bodies. Another said 15 casualties were in intensive care. Both asked that their names not be published because they are not authorized to speak to reporters.
Nigeria's military has promised increased security but appears incapable of halting a stream of attacks by extremists holding more than 250 schoolgirls hostage.
The kidnapping of the girls two months ago and failure of Nigeria's military and government to rescue them has roused international concern. The United States is searching for the girls with drones and has sent experts along with Britain and France to help in counter-terrorism tactics and hostage negotiation.
Boko Haram's leader Abubakar Shekau has threatened to sell the girls into slavery unless the government agrees to exchange them for detained extremists, but President Goodluck Jonathan has said he will not exchange prisoners. Nigeria's military has said it knows where the girls are but that any military campaign could get them killed.
Boko Haram wants to enforce an Islamic state in Nigeria, Africa's biggest oil producer with a population almost equally divided between Christians and Muslims.