GOMBE, Nigeria - A car bomb went off near a stadium in the northeastern Nigerian city of Gombe on Monday, a few minutes after President Goodluck Jonathan left a party rally there, killing one person and wounding 18.

A Reuters photographer said the bomb exploded about 200 metres (220 yards) from the stadium, engulfing the car in flames, while residents fled in panic.

A hospital source said one body had been brought in and 18 people were being treated for wounds, some of them serious.

There was no immediate claim of responsibility, although suspicion is likely to fall on Islamist militant group Boko Haram, which has attacked Gombe several times. On Sunday a suicide bombing near a mosque in the market area there killed five people and wounded eight.

Nigeria is due to hold a presidential election on Feb. 14, pitting the ruling People’s Democratic Party’s (PDP) Jonathan against former military ruler Muhammadu Buhari for the opposition All Progressives Congress (APC).

Both candidates are wrapping up their campaigns for what is expected to be the most closely fought election since the end of military rule in 1999.

The International Criminal Court (ICC) has warned Nigeria’s leaders not to stir up violence around the poll.

APC supporters and the ruling PDP have already clashed in street battles that have killed several people.

Boko Haram militants are stepping up their campaign of violence ahead of the election. The military repelled an attack by insurgents on the outskirts of the northeast’s main city of Maiduguri on Sunday, their second assault in a week on a city they hope to make the capital of a breakaway Islamist state.

The Islamist group has become the main security threat to the stability of Nigeria, Africa’s biggest economy and top oil producer, and is a major campaign issue for Buhari, seen as tough on security when he was a military leader in the 1980s.

The insurgents also increasingly threaten Nigeria’s neighbours, and both Chadian and Cameroonian troops have fought them in the past few days.

The group has killed thousands of people, many of them civilians, and kidnapped hundreds while the government has struggled to forge an effective response.

Also on Monday, three bombs in succession struck High Court buildings in different parts of Nigeria’s oil producing hub of Rivers state, causing no casualties, police said.