Europe

UK police still think Westminster attacker acted alone

  • People look at tributes in Parliament Square, London, Saturday March 25, 2017, laid out for the victims of the Westminster attack on Wednesday. Khalid Masood killed four people and left more than two dozen hospitalized, including some with what have been described as catastrophic injuries. The Islamic State group claimed responsibility for the attack. (John Stillwell/PA via AP)

    People look at tributes in Parliament Square, London, Saturday March 25, 2017, laid out for the victims of the Westminster attack on Wednesday. Khalid Masood killed four people and left more than two dozen hospitalized, including some with what have been described as catastrophic injuries. The Islamic State group claimed responsibility for the attack. (John Stillwell/PA via AP)  (The Associated Press)

  • FILE - In this March 22, 2017 file photo, emergency personnel tend to an injured person outside Britain's Parliament after an attack by a British-born man. The attack was claimed by the Islamic State group, which is encouraging its followers to use vehicles to achieve bloodshed.  (Yui Mok/PA via AP, File)

    FILE - In this March 22, 2017 file photo, emergency personnel tend to an injured person outside Britain's Parliament after an attack by a British-born man. The attack was claimed by the Islamic State group, which is encouraging its followers to use vehicles to achieve bloodshed. (Yui Mok/PA via AP, File)  (The Associated Press)

  • People place flowers outside Britain's parliament in London, Saturday March 25, 2017, for the victims of the Westminster attack on Wednesday. Khalid Masood killed four people and left more than two dozen hospitalized, including some with what have been described as catastrophic injuries. The Islamic State group claimed responsibility for the attack.(AP Photo/Kirsty Wigglesworth)

    People place flowers outside Britain's parliament in London, Saturday March 25, 2017, for the victims of the Westminster attack on Wednesday. Khalid Masood killed four people and left more than two dozen hospitalized, including some with what have been described as catastrophic injuries. The Islamic State group claimed responsibility for the attack.(AP Photo/Kirsty Wigglesworth)  (The Associated Press)

British police investigating an assault on Parliament that claimed four victims and wounded dozens say they still believe the assailant acted alone.

Police said late Saturday there is no information indicating that further attacks are planned.

Deputy Assistant Commissioner Neil Basu said it may never be possible to fully determine the motives of attacker Khalid Masood, who was shot dead Wednesday after running over pedestrians with an SUV and fatally stabbing a policeman.

Basu said "that understanding may have died with him," as police appealed for people who knew Masood or saw him to contact investigators.

One man remains in custody in the case. He has not been charged or named.

Masood, 52, had convictions for violence and spent time in prison. He also worked in Saudi Arabia teaching English.