Lagos, Nigeria (CNN) -- Two blasts shook a Nigerian government office Monday shortly after a rebel group sent out a message that it had planted bombs around the building, according to officials. No officials were hurt in the explosions in Warri in southern Nigeria, said Delta state government spokesman Linus Chima. It was not immediately known whether anyone else was wounded. The Movement for the Emancipation of the Niger Delta (MEND) claimed responsibility. It was the group's first claim for an attack since calling off a cease-fire with the government in January. The bombs were mounted in vehicles located about 200 meters (656 feet) away from the building, Delta state Commissioner for Information Oma Djebah said in a statement. Officials were meeting in the building to discuss steps forward with amnesty given to militants who agreed to lay down their arms.
@highlight
Movement for the Emancipation of the Niger Delta (MEND) claimed responsibility
@highlight
No officials were hurt in the explosions in Warri in southern Nigeria
@highlight
MEND battling the government for fairer distribution of the country's oil wealth
@highlight
It was the group's first claim for an attack since calling off a cease-fire
In an e-mailed message, @placeholder had warned of three planted bombs, with the first to be detonated remotely at 11:30 a.m. (6:30 a.m.