The chief of staff of Guinea-Bissau's armed forces was killed in a bomb attack on Sunday at the military headquarters, three months after an assault on the presidential residence.
General Tagme Na Waie had said earlier this year that he had been targeted in a previous assassination attempt, highlighting the chronic instability of this west African country.
"The general was in his office when the bomb went off," his aide Lieutenant Colonel Bwam Nhamtchio told AFP by telephone, crying as he spoke.
"He was gravely wounded and did not survive his injuries.
"This is a loss for all of us," he said, adding that five others were hurt in the evening blast -- two of them seriously.
One of the general's bodyguards, speaking anonymously to AFP, said the bomb was placed under the stairway leading to Na Waie's office and the blast -- at around 8 pm (2000 GMT) -- resulted in the collapse of a large part of the main headquarters building, where his office was located.
"It was 7:45 when we arrived at the headquarters building," the bodyguard said by telephone.
"The chief of staff headed upstairs. He had just reached the first steps when the bomb was triggered. He was mortally injured."
The bodyguard continued: "One of my colleagues who was carrying his bag was seriously wounded."
Immediately after the explosion, a group of officers led by Major Samuel Fernandes told local radio stations to suspend their programmes immediately, journalists said.
"Stop the programmes, close your stations until we have all the news about what happened at the army headquarters," Fernandes was quoted as saying.
"It's also for the personal safety of you journalists."
The bombing is the latest in a series of acts of violence committed in the past four months amid deep disagreements between the army, the presidency and the ministry of internal administration.
On November 23, a group of military men carried out a night attack on the residence of President Joao Bernardo Vieira in Bissau, killing two guards.
In early January, General Na Waie said he escaped an assassination attempt when sentries opened fire at his car as it passed the presidential palace.
At the time his office demanded that all soldiers guarding the presidency, forming a "militia," should be sacked.
Three soldiers were arrested belonging to a group called "aguentas," formed in Conakry during the 1998-1999 civil war in Guinea-Bissau to support Vieira, who was then facing an uprising by part of his army.
Guinea-Bissau has experienced a wave of coups, attempted coups and mutinies since becoming independent from Portugal in 1974.
In recent years it has become a hub for South American drug traffickers en route to Europe, a trend which experts say has further undermined the already weak state institutions.
Na Waie's predecessor, General Verissimo Correia Seabra, was shot dead by soldiers in October 2004.