Fresh arrests have been made in the Manchester bombing probe after police carried out a controlled explosion during a raid on an address in the Cheetham Hill area of the city.
Two men aged 20 and 22 were held on suspicion of terror offences after officers used an explosive device to gain entry to the property, Greater Manchester Police (GMP) said.
The operation in the early hours of Saturday morning brings the number of suspects being held in custody to 11.
The development came as a vast security operation gets under way to protect hundreds of Spring Bank Holiday events across Britain this weekend.
More than 1,000 armed police are on standby as major spectacles, including the FA Cup Final at Wembley and the Premiership Rugby Final at Twickenham, are expected to draw tens of thousands of people into public spaces on Saturday.
Despite the country being placed on critical alert, police have urged people to go out and enjoy themselves.
Britain's senior counter-terror officer said "immense" progress had been made in the probe into the associates of suicide bomber Salman Abedi and a "large part" of his suspected network had been dismantled.
Police forces across the country have reviewed security at more than 1,300 events and 1,100 armed officers are on hand to protect gatherings.
Metropolitan Police Assistant Commissioner Mark Rowley told the public: "Enjoy yourselves and be reassured by the greater policing presence you will see.
"We can't let the terrorists win by dissuading us from going about our normal business."
As the public was urged to carry on with planned activities against a background of heightened security fears:
:: Details about the scale of a wider terror threat facing Britain emerged as figures indicated as many as 23,000 people have appeared on the radar of counter-terror agencies.
:: The number of arrests in the Manchester probe reached 13, with one man held amid reports of armed police swooping on a bus travelling towards Manchester city centre.
:: Eleven suspects, the youngest an 18-year-old man, remained in custody following days of intense police activity that saw a series of raids in Greater Manchester, Warwickshire and Merseyside.
:: Metropolitan Police Assistant Commissioner Mark Rowley said some "key players" had been arrested in connection with the attack and investigators had made significant "finds".
:: US singer Ariana Grande vowed to return to Manchester to play a benefit gig for fans caught up in the blast.
:: Theresa May will chair a meeting of the British government's Cobra emergency committee in Whitehall on Saturday morning.
On Friday evening a 44-year-old man was arrested in the Rusholme area of the city. Witnesses reported seeing armed police storm a bus on its way to the town centre at around 7pm.
A shopkeeper said he hid up to six terrified passengers in the back of his Spar store on Oxford Road while armed police and uniformed officers attended the scene.
Twenty-two people, including seven children, were killed and scores injured when Salman Abedi launched a suicide attack at Manchester Arena on Monday night.
The massacre was the worst terrorist atrocity to hit Britain since the July 7 attacks in London in 2005.
The blast occurred minutes after Grande left the stage while her fans, many of them young girls, filed out of the venue.
On Friday she pledged to return to the city to hold a benefit concert to raise money for the victims and their families.
She also urged fans to donate to the Manchester Evening News fundraising appeal, which has raised more than £5m.
Grande, 23, said: "Our response to this violence must be to come closer together, to help each other, to love more, to sing louder and to live more kindly and generously than we did before.
"We will not quit or operate in fear. We won't let this divide us. We won't let hate win."