UK police release six arrested over attack

British police say six of the 10 people being held in connection with the attack near Britain's Parliament have been released without charge.

The two women and four men were all arrested in the central England city of Birmingham, where attacker Khalid Masood recently lived. All had been arrested on suspicion of preparing terrorist acts.

Four other people remain in custody as police try to learn how Masood became radicalised and went on a rampage Wednesday in London with an SUV and knives that killed four people. He was later shot to death by police.

Police believe Masood acted alone but want to know whether others helped him prepare the attack.