Police have released CCTV images of two men they want to speak to in connection with alleged assaults.
The incidents happened in Halifax town centre, but it is believed the men may have links to Haworth, Keighley and Wilsden.
A 41-year-old man was attacked outside a fast-food restaurant in Old Market at about 5.45am on June 30.
He received facial injuries and was knocked unconscious.
The assailants then turned on a Good Samaritan, a 59-year-old man, who had tried to help the victim. He was attacked and required stitches for a head wound.
Both suspects are white and believed to be in their mid to late 20s. One is described as about 5ft 8in to 5ft 10in tall, well built, with shaven, dark brown hair.
He was wearing dark trousers and dark shoes, and had tattoos down both arms.
The other is about 5ft 1in to 5ft 5in tall and of medium build. He had short, fair hair and was wearing a light-coloured top.
A police spokesman said: “Both men are known to have left the scene in a taxi, which picked up two other men and travelled to Wilsden, Haworth and Keighley.”
Anyone who recognises the men is asked to contact PC Sarah-Jane Brown at Halifax Police on 101 or Crimestoppers on 0800 555111.
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