At around 4.30pm on Tuesday, October 24, a teenage boy reported he was approached by a man when with his friend in Bellmead Park.
The man demanded the boy hand over his coat, it is alleged.
It was reported that the man had a knife tucked into his waistband at the time.
The boy was unharmed and managed to get away while the man is said to have walked off empty-handed towards Taco Bell in Moulsham Street.
Shortly after this attempted robbery, a man approached another teenage boy in the underpass at Parkway and Moulsham Street, allegedly demanding his coat.
It is alleged had a knife tucked into his waistband.
This victim handed his coat over and the man is said to have left with the boy’s Canada Goose Jacket, out of the underpass and back towards Baddow Road.
An Essex Police spokesman said: “If you have any information, CCTV, dash cam or other footage in relation to this incident, then please get in contact with us.
“You can let us know by submitting a report on our website or by using our online Live Chat service.
“If you would like to make an anonymous report, you can contact independent charity on Twitter at @CrimestoppersUK, by visiting their website or by calling 0800 555 111.”
“Quote crime reference 42/191191/23.”