Police have warned people not to approach Francis O’Donoghue, 27, and believe he could be hiding out with friends or relatives at a site outside Essex.
Mr O’Donoghue (pictured) is believed to have been at his home on farmland in Navestock when two men were shot at the site on Tuesday, August 27.
The attack followed “an ongoing neighbour feud”, officers have said.
Armed police remained at the farm overnight after the shooting and are also guarding the victims while they are kept in hospital.
Following treatment for gunshot wounds to the chest and legs, both men are said to be “recovering well”.
“We have taken several witness statements which all suggest that Francis O’Donoghue was at the site at the time of the shooting and so our focus is primarily now on finding him.,” said Superintendent Trevor Roe from Essex Police.
“This attack was the culmination of an ongoing neighbour feud which began outside a shop in Harold Wood earlier that Tuesday afternoon.
“We are working with all UK police forces, and especially the Metropolitan Police and Hertfordshire, to ensure they keep a look out for Francis.
“Again, we would urge anyone who knows him to avoid him purely because he is in possession of a handgun and those who come into contact with him should call us immediately.
“There is nothing though to suggest that people in the wider community are at risk of being injured.”
Mr O’Donoghue is described as white, in his late 20s, approximately 5ft 11ins tall and of medium build. He has short-brown hair, protruding ears and speaks with an Irish accent.
Anyone with information in connection with this shooting should contact detectives at Harlow’s Major Investigation Team on 101, email them on SCDappeals@essex.pnn.police.uk or call Crimestoppers anonymously on 0800 555111.
Anyone who knows of Mr O’Donoghue’s whereabouts is urged to call 999.