Armed police are guarding the streets in a major security operation amid fears of another terror attack this Bank Holiday weekend.
More than 1,000 police are on standby as major events, including the FA Cup Final at Wembley and Premiership Rugby Final at Twickenham, draw thousands over the weekend.
Hospital staff in 27 cities have also been warned to be on high alert. It comes as security is stepped up around the country following the Manchester terror attack which killed 22, including an eight-year-old girl.
Police made two further arrests overnight bringing the total held in custody to 11.
Greater Manchester Police said they carried out a controlled explosion to gain entry to the house in Cheetham Hill, north of the city centre.
A 16-year-old boy and a 34-year-old woman arrested were later released without charge.
The arrests at Cheetham Hill followed searches at a separate property in the area and another address in the Longsight area, in south Manchester, and police activity around Manchester is expected throughout the weekend.
Despite the country being on critical alert - the highest terror threat - police urged people to go out and enjoy themselves.
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."
Mr Rowley, Britain's most senior counter-terrorism officer, said police have now "got hold of a large part" of the terror network behind the Manchester bombing in which 22 people were killed.
Among those in custody is the brother of Manchester suicide bomber Salman Abedi, who was arrested in Whalley Range, south Manchester, on Tuesday.
WHAT EVENTS ARE GOING AHEAD THIS WEEKEND?
FA Cup final, Wembley - The Duke of Cambridge and Labour leader Jeremy Corbyn are expected to join tens of thousands of Arsenal and Chelsea fans at the north-west London stadium. The Football Association said enhanced security measures will be in place and fans are urged to arrive at least an hour before the 5.30pm kick-off.
Premiership Rugby final, Twickenham - Exeter Chiefs battle Wasps in south-west London, with kick-off scheduled for 2.30pm after a minute's silence for the victims of Monday's attack. England Rugby advised fans to allow extra time to access the stadium and avoid bringing bags where possible.
Radio 1's Big Weekend, Hull -Music fans heading to see Katy Perry, Little Mix, Biffy Clyro and others should allow extra time to undergo two rounds of security procedures. Police will be on hand at checks at transport hubs and a second check will be carried out at the site entrances.
Birmingham Pride - The parade begins at midday with a large number of police officers, specials and police staff on hand to keep the public safe, West Midlands Police said. Anyone who sees something suspicious is urged to tell a police officer or member of security staff.
Chelsea Flower Show, London - Visitors on the last day of the show are urged to "remain extra vigilant" and report any concerns to staff or security immediately. Organisers say they are continuing to work closely with the Metropolitan Police in light of recent events.
Great Manchester Run - Thousands of defiant runners and spectators are expected to turn out for the 10k race. Participants should have received direct instructions from organisers by email.
Vitality Westminster Mile, London - Organisers said they are working closely with the Metropolitan Police, the Mayor's Office and other authorities on additional security measures for runners and spectators on The Mall.
Radio 1's Big Weekend day two, Hull - Concert-goers should expect the same security measures as were in place on Saturday.
WHAT EVENTS ARE CANCELLED?
The only cancelled event this weekend is a screening of the FA Cup final that was due to be shown on Saturday at the Emirates Stadium.
However, both Arsenal and Chelsea have said the FA Cup winners will not stage parades on Sunday to avoid placing additional pressure on the police.