Two of the victims of the hit-and-run incidents in Cardiff last year had to leave the court room when footage was shown of them being dragged under the van that the defendant was driving.
Gill White and her daughter Rebecca were two of the most severely injured victims in the attacks.
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The Metropolitan Police Federation, which set up the official JustGiving site, said it felt a "suitable amount" had been collected.
There is no evidence the Westminster attacker Khalid Masood was associated with so-called Islamic State or al Qaeda, the Met Police said.
Janet Ajao said in a statement: "I do not condone his actions nor support the beliefs he held that led to him committing this atrocity."