The attack happened in Strabane last night and cops believe the men fled back across the border.
The gang of up to 20 men were involved in the attack at a bar in the Abercorn Square area of Strabane.
Four men in total were injured incluidng the bar’s owner.
Two of the victims, believed to be brothers in their 30s, are in a serious but not life-threatening condition in hospital.
The owner of the bar was also stabbed in the hand during the attack which happened around 9.30pm last night.
Local councillor Eugene McMenamin told donegaldaily.com he understand the gang behind the attack fled across the border to Donegal.
“It is a miracle that nobody was killed during this brutal attack. The fact that four men were stabbed says it all.
“This was a brutal attack during which a knife or even knives were produced. It’s bad enough that four people were stabbed but somebody could have been killed.
“I have spoken with the police and I understand that these men, or some of them, are from Co Donegal and fled across the border after this attack happened.
“I would appeal to anyone who knows who may have been behind this attack to contact the Gardai or the PSNI and make sure that these people are brought to justice,” he said.
He stressed that the bar in which the attack happened was a very well-run premises.
“I personally know the owner of this premises and he runs a very good business. This is a very respectable bar and nothing like this has ever happened before.
“There has never been a knife-culture in Strabane and it’s not a good development. The sad thing is that people had a great day for St.Patrick’s Day up until this happened,” he said.