Synagogue-goers were antisemitically abused by a man in a white van as they made their way home.
Police have said a person driving a white Ford Transit van last Saturday in Borehamwood, Hertfordshire, shouted offensive language at a group walking along Deacons Hill Road at around 1pm.
It is understood that the driver made reference to Hitler and the “gas chambers”.
A Hertfordshire police spokeswoman said: “The matter is being investigated as a public order hate crime and investigations are ongoing.
“No arrests have been made at this time.”
She confirmed that a 26-year-old man from Borehamwood was interviewed under caution, adding that investigations are on-going.
The alleged offence was reported to Jewish security group, the Community Security Trust.
CST director of communications Mark Gardner said: “CST received reports of antisemitic abuse being shouted by men in a van, as they drove past small groups of congregants leaving shul. We have the registration number and it is being followed up by police.”