An elderly man fell into the road after being attacked.
The man, a 78-year-old, was hit on the head and fell over when he was crossing Upper High Street, near the New Amsterdam pub in Worthing.
He was helped home by passersby but later attended hospital for treatment of a serious shoulder injury.
The assault happened around 3.40pm on Monday, October 9.
Investigating officers have been making inquiries including house visits and CCTV trawls and believe the area was busy with people who may have seen what happened.
Now, police are appealing for any witnesses, or anyone who may have any other relevant information, to get in touch.
A spokeswoman for Sussex Police said: “We would also like to speak to anyone who may have captured any relevant doorbell or dash cam footage from the area at the relevant time.
“Anyone with information is asked to contact police online or by calling 101 quoting serial 1023 of 09/10.”
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