The assistant commissioner of the Metropolitan Police has outlined to MPs the scale of the force's inquiry into the murder of soldier Lee Rigby.
Giving evidence to the Home Affairs Select Committee, Cressida Dick said 600 officers were involved in the police operation at its peak, including 100 counter-terrorism officers.
She told the group of cross-party MPs that 17 addresses had been searched, 12 arrests made and six cars seized as part of the Met's investigation into the shock killing of the serving British soldier.
In addition, some 2,649 pieces of evidence have been uncovered.
Father-of-one Drummer Rigby was hacked to death in broad daylight near Woolwich barracks in south-east London on May 22.
Ms Dick also defended the Met's response to the attack, saying both the unarmed and armed response times were within what she would expect.
But she added: "I cannot possibly put myself in the shoes of people who were at that horrific scene, many of them completely traumatised I’m sure by what had happened, waiting for police to arrive."
She said she was also "very comfortable" with the command and control of the response.
"As soon as the call came in saying somebody had knives and a gun, the armed response vehicle was deployed and I believe in the intervening minutes there was very strong command and control in the way that we expect, in the way that we train for," she said.
The police chief's evidence comes after two men - Michael Adebolajo, 28, and Michael Adebowale, 22 - appeared in separate courts charged with Drummer Rigby's murder.
Ms Dick told the MPs that she could not rule out another attack like the one in Woolwich - from both external threats and "home grown terrorists".
She said: "The threat is very real, the country remains at the threat level of substantial and we have to deal with a threat that comes from a very wide range of sources.
" ... So an attack is a strong possibility and we have a big changing, morphing threat to deal with."
Ms Dick revealed that Scotland Yard is closely watching radical cleric Anjem Choudary to see if his proclamations break the law, although she admitted that "so-called preachers of hate" usually know where to stop.
Her comments came amid reports that Choudary has made controversial remarks about the murder of father-of-one Drummer Lee Rigby near Woolwich barracks.
The former spokesman for the now-banned Islamist group Islam4UK, who admitted knowing one of the men charged with the soldier's murder, is also understood to be receiving police protection outside his east London home.
Asked by committee chair Keith Vaz if that was the case Ms Dick said: "We constantly risk-assess what's going on around a number of different people who have high profiles in the media.
"In the case of somebody like Mr Choudary, we are constantly assessing, of course, whether any of his proclamations are breaking the criminal law and working with the CPS to ensure that if he is breaking the criminal law we know about it very swiftly."
She added that if officers fear someone's "life is at risk or indeed that there's going to be a major disorder around them", then they may put a police presence in place.
After the committee's first hearing, attended by senior Cabinet members, David Cameron said his new task force would look into whether more could be done to tackle radicalisation in schools, colleges and universities.