A nursery worker was slashed with a knife by three women in Wanstead on Wednesday as she walked from the railway station to a nursery where she worked.
Paul Ashmore, a 31 year old from South Woodford mixing and mastering engineer in South Woodford, said his fiancee and child were both caught up in a lockdown.
He said: "My instant thought was to collect my fiancee and kid and get them to safety not knowing the full extent of what was happening. But I was thinking the worst."
The victim of the attack, a white woman aged in her 30s, was attacked by three Asian women dressed all in black and shouting "Allah", according to a colleague at Little Diamonds nursery.
Karrien Stevens, the operations manager, said: "They pulled her to the ground, punched her, kicked her. One of them pulled out a knife and cut her arm from her wrist to her elbow."
"She is shaken up, she's emotionally a bit of a wreck, they did scare her, but she is OK, she is a strong staff member."
Stevens also said the worker did not know her attackers, adding that they fled the scene when a passer-by intervened. No arrests have been made.
A Metropolitan Police spokesman said: "Counter-terror officers are aware of the incident but it is not being treated as terrorism at this stage."
Mayor of London Sadiq Khan said: "It's early days yet but the police are taking it very seriously. Various lines of inquiries are being followed. And I'm confident that justice will be done."