The men, suspected of hacking the off-duty soldier to death while horrified bystanders watched, boasted of their exploits and warned of more violence in images recorded on witnesses' mobile phones. Holding bloody knives and a meat cleaver, they waited for the arrival of police, who shot them in the legs, according to a passerby who tried to save the dying soldier.
Prime Minister David Cameron vowed that Britain would not be cowed by the horrific violence, and that it would reject "the poisonous narrative of extremism on which this violence feeds." Indeed, there were few signs of alarm in the capital city, which has been hit by terrorist attacks during a long confrontation with the Irish Republican Army and more recently by al-Qaida-inspired attacks.
"It's hateful, it's horrific and upsetting. But it doesn't seem to have made much of a difference," Christian White, 43, said at King's Cross station, close to the site of a subway bomb in July 2005. "Londoners are used to living in a city where life is complicated."
Even so, security was increased at military barracks and installations in the capital, with extra armed guards added in many cases. Wednesday's attack took place near a military barracks in the Woolwich area of south London.
There was little hard information available about the wounded suspects. Police gave no details of their injuries or conditions.
They did confirm that the victim was a serving British soldier. His family has asked that his name not be immediately released.
After the killing, one of the attackers was recorded on numerous amateur videos making threats, explaining the reason for the crime, and shouting political slogans while gesturing with bloodied hands and waving a meat cleaver.
"We swear by almighty Allah we will never stop fighting you," the man declared, complaining about British troops fighting Muslims. "We must fight them as they fight us."
The camera then panned away to show a body lying on the ground. This video, with its venomous threats, may provide the lasting image of the tragedy.
A British government official said both suspects were part of previous security services investigations for possible terror links.
The official, who spoke on condition of anonymity because he was not authorized to speak about the investigation, said he could not provide other details because the suspects may face trial. Investigations by Britain's domestic security service, MI5, can include undercover surveillance, phone tapping and communications intercepts.
Police in the county of Lincolnshire in eastern England said a property was being searched in connection to the attack in Woolwich. Police said a search warrant had been obtained but would not provide details about the search. Police were also scouring the attack site for further clues.
The incident unfolded Wednesday afternoon when officers responded to reports of an assault just a few blocks from the Royal Artillery Barracks in Woolwich.
Fred Oyat, 44, who lives in a high-rise nearby, said he heard four gunshots and went straight to the window.
"I saw one man lying there bleeding, another lying on the pavement being disarmed. A policeman was pointing a gun at him. A third man was lying further up the street. ... He was bleeding profusely," Oyat said. "There were four knives on the ground - big kitchen knives. The knives were very bloody."
Witnesses recounted seeing the suspects - armed with meat cleavers and possibly a firearm - rushing toward police when officers arrived on the scene. Police then opened fire.
Images from the scene showed a blue car that appeared to have been used in the attack, its hood crushed and rammed into a signpost on a sidewalk that was smeared with blood. A number of weapons - including butchers' knives, a machete and a meat cleaver - were strewn on the street.
The Associated Press examined the footage to verify its authenticity, cross-referencing images from the scene, aerial shots, the location of a car behind the alleged attacker and the appearance of a body and a car in the background. There was no immediate way for the AP to verify who the cameraman was.
Other images showed the second suspect clutching a long knife as he engaged in conversation with a woman who British media said tried to intervene to prevent further bloodshed.
The Daily Telegraph identified the woman as Ingrid Loyau-Kennett, 48, and said she confronted the attackers, telling them: "It is only you versus many people. You are going to lose."
Britain has been at the heart of several terror attacks or plots in recent years, the most deadly being the 2005 rush-hour suicide bombings when 52 commuters were killed. More recently, Parviz Khan was convicted in 2008 of plotting to kidnap and behead a British Muslim soldier in Birmingham.
Late Wednesday, riot police fanned out in Woolwich as about 50 men waving the flag of the far-right English Defense League gathered, singing nationalistic songs and shouting obscenities about the Quran.
Muslim religious groups and charities were quick to condemn the attack and urged police to calm tensions. The Muslim Council of Britain called it a "barbaric act that has no basis in Islam," adding that "no cause justifies this murder."
Associated Press writers Cassandra Vinograd, Sylvia Hui and Danica Kirka in London contributed to this report.