Wife of the man who killed four people outside Britain's Parliament last week condemned the attack Tuesday, saying she is "saddened and shocked."

"I express my condolences to the families of the victims that have died, and wish a speedy recovery to all the injured," Rohey Hydara said in statement released through London police.

Khalid Masood's widow added: "I would like to request privacy for our family, especially the children, at this difficult time."

Police believe Masood - a 52-year-old Briton with convictions for violent crimes who had spent two years in Saudi Arabia - acted alone in last Wednesday's knife and car attack. But they are trying to determine whether others helped inspire or direct his actions.

The so-called Islamic State group has claimed he was a "soldier" responding to its repeated calls for attacks on western nations. Police say they have found "no evidence" of any links to Islamic State or al-Qaida.

Masood was killed by police after fatally stabbing an officer and running down pedestrians with his rented SUV. It was the deadliest extremist attack in Britain in 12 years.

Police say there is no intelligence suggesting further attacks are planned, but police presence has been increased at some London sites and also outside Windsor Castle, one of Queen Elizabeth II's favored residences.

Thames Valley Police said Monday night that extra security barriers are being placed around the castle before the next 'Changing the Guard' ceremony planned for Wednesday.

"While there is no intelligence to indicate a specific threat to Windsor, recent events in Westminster clearly highlight the need for extra security measures to be introduced," said assistant chief Dave Hardcastle.

AP