Britain is bracing for clashes with right-wing activists and possible copycat terror attacks by Islamic extremists after the slaying of a young soldier.
London police said more than 1,000 officers will be sent to potential trouble spots with armed response units. Most British police officers don't carry weapons.
The attack was captured on video by passers-by and made for gruesome viewing – one man is seen with his hands stained red with blood and holding two butcher's knives as he angrily complained about the British government and troops in foreign lands. A lifeless body is behind him.
Terror analysts say the attackers wanted to inspire copycat attacks, and that they are seeing an increase in online chatter calling for such attacks.
"We can see the tempo being raised," said Maajid Nawaz, a former jihadist who is now with the London-based anti-extremist Quilliam Foundation. "One of the reasons why these guys acted in this theatrical way was because of the propaganda effect. The nature of these attacks are that they are so easy to do, and we have definitely seen an increase in chatter calling for such things."
A British government source confirmed the increase in chatter since Wednesday's attack but said no specific or credible plots had been detected.
Britain's terror threat level has remained unchanged at "substantial" – the middle of five possible rankings – since the slaying of Lee Rigby (25).
Police said that an autopsy on Rigby's remains had been conducted but that the cause of death has not been confirmed. An inquest will be held.
His anguished widow, Rebecca Rigby, spoke of her loss yesterday at a news conference at his unit's headquarters.
"I love Lee and always will," she said, sobbing. "I am proud to be his wife and he was due to come up this weekend so we could continue our future together as a family.
"You don't expect it to happen when he's in the UK. You think they're safe."
His stepfather, Ian Rigby, read a statement, including the final text the soldier had sent to his mother, who was too upset to speak: "The last text he sent to his mum read, 'Goodnight mum, I hope you had a fantastic day today because you are the most fantastic and one in a million mum that anyone could ever wish for. Thank you for supporting me all these years, you're not just my mum, you're my best friend. So goodnight, love you loads.'"
Right-wing extremists said they would be holding demonstrations and there were some signs of a backlash against Muslims, including two incidents late Thursday night. In Lincolnshire, eastern England, police said 11 teenagers were arrested after they attacked a local mosque following a party.
In the other attack, a burning bottle was thrown at a mosque in Bletchley, central England, while people inside were praying, police said.
Lincolnshire police also arrested a 22-year-old man on suspicion of inciting racial hatred via a Facebook post.
The two main suspects in the murder inquiry, who were shot after rushing police on the scene, are still in hospital.