Police in London are continuing to investigate Khalid Masood, who drove his car into pedestrians on Westminster Bridge and stabbed a police officer to death before being shot dead.

Wednesday's attack that left four people dead has triggered widespread condemnation.

Investigators in the UK say that the British-born Muslim convert went by many aliases, including Adrian Elms and Adrian Russell Ajao, and that their probe focuses on understanding Masood's motivation, preparation and his associates.

A total of 10 people were arrested in London and Birmingham in connection with the attack, of which six people have been released.

TRT World's Sarah Morice has more details.