A man out running in Hitchin was forced to defend himself when "someone ran at him with a six-inch knife", his shocked partner has told the Comet.
The attack happened in Queen Street at around 10.30pm on Friday.
The victim's partner said: "Out of nowhere, someone ran at him with a six-inch knife outside Cannon House flats. If he had not defended himself, two of the blows would have hit him.
"Very fortunately, a taxi driver was passing and my partner used his initiative to run into the road to stop him, and got in for safety.
"The guy with the knife apparently ran off.
"Very few witnesses stopped. If they knew what they were witnessing, they may have."
Police in North Hertfordshire say they are investigating the incident.
A spokesperson for Hertfordshire police said: "At around 10.45pm on Friday (March 8), it was reported that a man was approached by another man who was in possession of a bladed weapon.
"No injuries were reported.
"Enquiries are continuing and anyone with information can report it online at herts.police.uk/report, speak to an operator in the Force Communications Room via the online web chat at herts.police.uk/contact or call the non-emergency number 101, quoting crime reference 41/19713/24.
"Alternatively, you can stay anonymous by contacting the independent charity Crimestoppers on 0800 555 111 or via their untraceable online form at crimestoppers-uk.org."
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