LONDON -- Police officers, Muslim youths and hundreds of others linked hands Wednesday on Westminster Bridge to honour the four people who died in an attack that started on the span a week earlier.

The bridge fell silent at 2:40 p.m. to mark the moment when Khalid Masood began mowing down pedestrians, killing three. Masood then fatally stabbed a policeman in a courtyard on the grounds of Parliament.

Police say Masood, a native Briton, was inspired by extremist ideology, but that there's no evidence he had direct links to the Islamic State group or al-Qaida. One 30-year-old man remains in custody; a second man was released without charge Wednesday.

Nurses and doctors from St Thomas' hospital, where many of the injured were treated, joined the vigil on the bridge, which was closed for the event.

Schoolchildren clutching yellow roses held signs reading, "Islam says no to terror" and "Please don't kill innocent people" as they walked across the span that crosses the River Thames.

Hundreds of members of the Ahmadiyya Muslim Youth Association wore T-shirts with the message "I am a Muslim, ask me anything".

Zafir Malik, an imam from the association, said the group wanted to show the attack had nothing to do with Islam.

"We're here to show that we are united with our fellow countrymen and remembering those who have fallen, especially (police constable) Keith Palmer," he said. "We are here and showing our solidarity for the country."

The commemoration came as an inquest opened into the deaths of American tourist Kurt Cochran, 54, retired window cleaner Leslie Rhodes, 75, school administrator Aysha Frade, 44, and Palmer, 48.

Detective Superintendent John Crossley said more than 35 people were hurt in the March 22 attack, with injuries ranging from cuts and bruises to extensive bone fractures.

"The driver mounted the pavement twice in an apparently deliberate attempt to target pedestrians, before mounting the pavement for a final time and crashing his vehicle into the east parliament gates of the Houses of Parliament," Crossley said.