JOS, Nigeria (Reuters) - Clashes broke out between armed Christian and Muslim groups near the central Nigerian city of Jos on Sunday, a Reuters witness said, after Christmas Eve bombings in the region killed more than 30 people. Buildings were set ablaze and people were seen running for cover as the police and military arrived on the scene in an effort to disperse crowds. This correspondent saw dozens of buildings on fire and injured people covered in blood being dragged by friends and family to hospital. The unrest was triggered by explosions on Christmas Eve in villages near Jos, capital of Plateau state, that killed at least 32 people and left 74 critically injured. The Red Cross said on Saturday it was not in a position to state the total number of deaths caused by the explosions but confirmed that 95 were seriously injured in hospital. Vice President Namadi Sambo will travel to Jos on late Sunday. The vice president is on his way to Jos to make an effort to quell this crisis, Sambos spokesman said. The unrest has come at a difficult time for President Goodluck Jonathan, who is running a controversial campaign ahead of the ruling partys primaries on January 13. A ruling party pact says that power within the Peoples Democratic Party (PDP) should rotate between the mostly Muslim north and largely Christian south every two terms. Jonathan is a southerner who inherited office when President Umaru YarAdua, a northerner, died during his first term this year and some northern factions in the ruling party are opposed to his candidacy. Jonathan faces a challenge from former Vice President Atiku Abubakar for the ruling party nomination, and some fear any unrest in Africas most populous nation will be exploited by rivals during campaigning. The governor of Plateau state has said the bombings were politically motivated terrorism, aimed at pitting Christians against Muslims to start another round of violence. Christians, Muslims and animists from a patchwork of ethnic groups live peacefully side by side in most Nigerian cities. But hundreds of people died in religious and ethnic clashes at the start of the year in the central Middle Belt and there are fears politicians could try to stoke such rivalries as the elections approach. The tensions are rooted in decades of resentment between indigenous groups, mostly Christian or animist, who are vying for control of fertile farmlands and for economic and political power with mostly Muslim migrants and settlers from the north. The African Union (AU) on Saturday released a statement condemning the Christmas Eve bombings and offered its condolences to the families of those who have died.