Witnesses say a suicide bomber on a tricycle taxi packed with explosives entered the Crossfire venue, a popular viewing center in Damaturu, state capital of Yobe, in northeast Nigeria shortly after the tournament hosts, Brazil kicked off against Mexico at 8:00 p.m. (1900 GMT).
Police Assistant Superintendent Nathan Cheghan confirmed the explosion but said rescue workers were being careful for fear of secondary explosions. Al Jazeera reports that agencies are reporting several pickup trucks (containing casualties) have arrived at a hospital at Damaturu.
No terrorist group has claimed responsibility for the deadly bombing. However, officials say the bombing has the markings of the Boko Haram, the terrorist group has targeted football viewing centers and sports bars in the past.
Damaturu, the capital of Yobe state has been devastated by attacks by Boko Haram, the terrorist group responsible for abducting more than 200 girls from a school in neighbouring Borno state in April.
The Nigerian government issued an advisory to residents two days ago to avoid gathering in public to watch the World Cup, concerned about possible attacks. Authorities in Adamawa, also in northeast Nigeria, last week closed viewing centers, where large crowds gather to watch matches on the big screen, while the central state of Plateau followed suit days later.
Worldwide, sports arenas and stadiums hosting high school, college, and professional sports have been popular targets for terrorists groups. "Soft targets" such as sports arenas, shopping malls and mass transportation hubs where crowds gather are attractive terrorist targets due to the lax security measures that make them cheap and relatively easy targets.
The 2013 Boston Marathon was an especially easy and attractive target for terrorists due to the enormous international attention. News outlets from across the world cover it, and runners from 96 countries participated in this year's marathon. The Olympic games, including the 1972 Munich Olympics and the 1996 Olympics at Centennial Olympic Park.in Atlanta, Georgia are other examples of sporting venues where terrorists attacked.
The U.S. Department of Homeland Security and FBI have issued security bulletins to state and local law enforcement agencies in recent years after recovering al Qaeda's training manuals during raids of suspected terrorists homes. The al Qaeda handbook lists "blasting and destroying the places of amusement, immorality and sin and attacking vital economic centers as a key objective."