A Tamil Tiger suicide bomber killed Maj Gen Parami Kulatunga, the Sri Lankan Army's Deputy Chief of Staff, and two others at Pannipitiya, 15 kms outside Colombo on Monday.
Gen Kulatunga was third in the Army hierarchy.
According to the Army media division, the suicide bomber, who was on a motorbike, rammed into the vehicle in which the General was travelling.
The attack took place in a busy junction at 7.45 am when there were school going children and office goers on the road.
The Director of the Colombo National Hospital said that Gen Kulatunga's dead body was among the three brought to the hospital.
The others dead were diver Sergeant Gomes and Corporal Buddhika, the bodyguard.
TV channels showed footage of the burning vehicle, an inferno no one could have survived.
Many standing by were injured, police said.
Maj Gen Kulatunga was a tough General and had served as Security Forces Commader in the forward areas of Wanni, Mannar, Vavuniya and Trincomalee.
LTTE's "continued commitment to terrorism"
President Mahinda Rajapaksa blamed the LTTE for the dastardly assassination of Gen Kulatunga.
In a special message, he said that the killing was "another example of the LTTE's continued commitment to terrorism and its cowardly use of suicide killers, deserving contempt and condemnation."
Addressing the international community, the President said: "This unabated violence by the LTTE should attract the opprobrium of the entire civilised world."
"It is a reminder to the international community, and to the Tamil people, that the LTTE remains an organisation dedicated to pursue violent means, especially the use of terror to achieve objectives, which are far removed from the actual needs of the Tamil people."
"This act of violence targeting a high ranking officer of the Sri Lankan Army, and the callous disregard for the safety of civilians in such attacks, will not frighten either the civilians or the security forces, nor deter them from overcoming the LTTE and its terror."
"On this sad occasion I wish to re-state my commitment to protect the sovereignty and territorial integrity of Sri Lanka."
Second attempt in two months
This is the second major Army target, which the LTTE had taken on in the past two months.
On April 25, a suicide bomber tried to kill Army Commander Lt Gen Sarath Fonseka. He escaped with serious injuries. He is away in Singapore for treatment.
Political observers say that in the tit for tat killings going on in the ugly shadow war, the assassination of Maj Gen Kulatunga followed the killing of two top ranking LTTE military commanders, Lt Col Ramanan of Batticaloa and Lt Col Mahindi of Mannar, allegedly by Tamil paramilitaries aligned with the Sri Lankan Army.
Attack came in the wake of President's offer of two-week ceasefire
The assassination of Gen.Kulatunga came within a week of Sri Lankan President Mahinda Rajapaksa's offering the LTTE, a two-week de facto ceasefire and direct talks, to resolve the ethnic issue without the facilitation of Norway.
He had also offered to rein in the renegade LTTE leader Karuna, according to media reports on Sunday.
The LTTE is believed to have rejected the offer on the grounds that it was a bid to drive a wedge between it and the Norwegians.
Meanwhile, ceasefire monitoring by the Scandinavians came to a standstill due to a conflict over the acceptability of monitors from the European Union (EU) after the EU banned the LTTE.