A former community centre in Leeds has become a focus of police hunting the London bombers, and nearby residents have had to leave their homes.
Residents evacuated from the Hyde Park area returned on Thursday
Bomb disposal experts examined the building, said to be a meeting place for Muslim youths, close to the Beeston home of bomber Shehzad Tanweer.
Police told residents to pack enough clothes for three days.
Meanwhile, officers continued to search a house in Aylesbury, Bucks, where the fourth bomber is said to have lived.
The British Red Cross said the Leeds residents who had been moved would be given bed and breakfast accommodation at Leeds Metropolitan University, with a day centre set up at the Leeds Indoor Bowls Centre.
Mohammad Sidique Khan: Aged 30, from Beeston, Leeds, recently moved to Dewsbury, married with baby. ID found at Edgware Road blast site.
Hasib Mir Hussain: Aged 18, lived Holbeck, Leeds. Reported missing on day of bombings. Said to have turned very religious two years ago. ID found in No 30 bus.
Shehzad Tanweer: Aged 22, born Bradford, lived Beeston, Leeds. Studied religion in Pakistan. Forensic evidence linking him to Aldgate blast.
Fourth bomber: Still a question mark over his identity. Believed to be a friend of the others and from same area.
The police initially set up a 30m cordon around the former community centre on Lodge Lane and evacuated all of the houses within it.
They later extended the cordon and evacuated more people.
The Red Cross said it was preparing to look after up to 200 people.
A controlled explosion was reported in the area on Thursday morning.
An army bomb disposal unit was present at the scene of the search.
The move follows the evacuation on Tuesday of about 600 residents in the Hyde Park area of the city
They were evacuated following the discovery of a suspicious substance during a police raid on a house in the area.
Many were allowed back to their homes in Alexandra Grove after two nights as detectives confirmed the substance was not hazardous.
Police are also continuing their search of a house on Northern Road, Aylesbury, where they believe the fourth suicide bomber lived.
Detectives are almost certain that Jamaican-born Briton, Germain Lyndsay, is the fourth bomber.
Aylesbury is 20 miles from Luton, where the four bombers boarded a train to London.
Leeds North West MP Greg Mulholland said on Wednesday that the house police searched in Hyde Park was used as an operational base for those involved in the bombings.
He said materials used in the attacks may have been stored at the house.
Police are asking for anyone with information on the bombs to contact their anti-terrorist hotline on 0800 789 321.