"The threat level remains at critical and there will be further investigations and part of the operation later today", Rudd told reporters. "And you will have heard consequently the Home Secretary's announcement that the threat level has reduced from Critical to Severe which of course means that an attack is highly likely".
Isis has claimed responsibility for the attack, which left 30 people injured when a bomb partially exploded on a District Line train on Friday morning.
Thirty people were injured in the explosion, none of them seriously, in the wake of the subway blast, prompting the police to stage a massive hunt for those who are responsible for the fifth terrorist attack in the country over the past six months.
One or two residents who spent the night elsewhere have been returning to the road to collect belongings - they are being allowed to do so only with a police escort to and from their home.
An 18-year-old man was detained in the departure lounge of Dover port, in Kent, and a 21-year-old man was held at a house in Hounslow, west London.
He was arrested under section 41 of the Terrorism Act and taken to a south London police station where he remains in custody.
Britain's National Health Service says all but one of the people wounded in the subway bombing attack have been released from the hospital.
Police are continuing to search a foster home in Sunbury-on-Thames, Surrey, in connection with the teenager's arrest on Saturday.
Rudd made the comments on BBC's Andrew Marr Show on Sunday, after Trump claimed the person who carried out the attack was known to British police.
The entire road was evacuated on Saturday while the initial investigations at the property were underway.