Police were called to reports a man had been stabbed at a garage in Highfield Road at around 3.20pm on Monday, February 14.
A local man in his 30s was found with "serious head injuries" and "stab wounds to his neck, back and arm" when emergency services arrived.
He was taken to hospital for treatment, where police said he remained in a "serious but stable condition".
A spokesman for Lancashire Police said: "Enquiries are ongoing and reassurance patrols have been increased in the area.
"Anyone with information or concerns can approach an officer."
On Thursday (February 17), detectives released CCTV footage of two men they wanted to speak to in connection with the attack.
The first man police want to speak to is described as white, with dark brown shaven hair.
He was seen wearing a black hooded top and dark blue pants at the time of the assault.
The second man is also described as white, with shoulder-length wavy dark brown hair.
He was wearing a black North Face coat with a red zip and grey jogging bottoms.
Anyone with information can contact the police by calling 101, quoting log number 0865 of February 14.
Alternatively, independent charity Crimestoppers can be contacted anonymously or 0800 555111 or online at crimestoppers-uk.org.
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