Two suicide car bombers targeted the offices of Nigerian newspaper This Day in the capital Abuja and the northern city of Kaduna today, killing at least four people, officials and witnesses said.
This Day is based in southern Nigeria and is broadly supportive of president Goodluck Jonathan's government, the main target for Islamist insurgent group Boko Haram.
There was no immediate claim of responsibility for the bombings.
A suicide bomber drove a jeep into the daily's Abuja office, killing himself and two others, witnesses said.
"We have collected three bodies but before we got here people had already been moved," Nigerian Red Cross spokesman Nwakpa Nwakpa told Reuters at the scene of the Abuja blast.
A witness saw the second attack in Kaduna, when a suicide car bomber drove into the This Day office compound and tried to detonate his explosives but was stopped by bystanders, who dragged him out of the vehicle.
The bomb later went off, killing at least one, police commissioner Mohammed Abubakar confirmed on the scene.
If the attackers were Boko Haram, it could mark a shift in tactics. Until now, their bombings have not targeted the press.Boko Haram has been fighting a low level insurgency against Mr Jonathan's administration for more than two years and has become the main security menace in Africa's top oil producer.
It has killed hundreds in bomb and gun attacks this year, mostly in northern towns and cities.In August last year, Boko Haram carried out a suicide car bombing at the United Nations building in Abuja that killed 25 people and prompted a ramp-up in security measures in the capital of the continent's most populous nation.
Sirens wailed as police and fire fighters rushed to the scene of the blast in Abuja today. Smoke billowed from the building, whose windows were all smashed.
Soldiers and police cordoned off the area, while emergency workers evacuated wounded on stretchers to waiting ambulances.
"The suicide bomber came in a jeep and rammed a vehicle into the gate," said Olusegun Adeniyi, chairman of the This Day editorial board. "Two of our security men died, and obviously the suicide bomber died too."
This Day's publisher, Nduka Obaigbena, is a prominent celebrity in Nigeria and puts on music, art and fashion events in cities in around the world.
Reuters