LAGOS, Nigeria - Bomb blasts struck Tuesday near army and air force bases on the outskirts of the central Nigerian city at the heart of riots last year that killed hundreds, officials said.

The explosions near the city of Kaduna caused some injuries, state police commissioner Bala Nasarawa said. However, he said he did not have any other details. Journalists working in the city said soldiers and security forces cordoned off the areas and blocked access to the sites immediately after the blasts. Soldiers also seized journalists' cameras.

Authorities said they received reports of a third explosion near a highway overpass in Kaduna, but had no other immediate details.

Emergency officials confirmed the blasts occurred at the base of the 1st Mechanized Division near the town of Kawo and at the air force's training base near Mando. The officials declined to be named given the sensitivity of the matter.

Maj. Gen. Raphael Isa, an army spokesman, said in a statement that a suicide bomber dressed in a military uniform attempted to drive a car bomb into the 1st Mechanized Division headquarters. Soldiers guarding the gate opened fire on the man, who died from gunshot wounds.

"The bomb exploded and shattered the glass that adorn the ... headquarters," Isa said. "The suicide bomber was the only casualty."

An air force spokesman could not be immediately reached for comment.

No one immediately claimed responsibility for the attacks. The blasts come as Nigeria faces increasingly bloody attacks from a radical Islamist sect known as Boko Haram. The sect has killed at least 270 people this year alone in its campaign to avenge Muslim deaths and implement strict Shariah law across multiethnic Nigeria, a nation of more than 160 million people.

The blasts also come after security agencies last week arrested a man they believe to be the sect's spokesman.

Kaduna, on Nigeria's dividing line between its largely Christian south and Muslim north, was at the heart of postelection violence in April. Mobs armed with machetes and poison-tipped arrows took over streets of Kaduna and the state's rural countryside after election officials declared President Goodluck Jonathan the winner. Followers of his main opponent, former military ruler Muhammadu Buhari, a Muslim, quickly alleged the vote had been rigged, though observers largely declared the vote fair.

Across the nation, at least 800 people died in the April rioting, Human Rights Watch said.

In Kaduna alone, more than 2,000 died as the government moved to enact Islamic Shariah law in 2000. In 2002, rioting over a newspaper article suggesting the prophet Muhammad would have married a Miss World pageant contestant killed dozens.