A Marks & Spencer worker was seriously injured after going to help a female shopper who was stabbed in the neck.
The female employee in her 40s is believed to have suffered wounds to her arms as she bravely tried to save the customer from a knife-wielding attacker.
The employee and the shopper, in her 60s, were set upon at 9.30am just after the doors opened at the Burnley store for the first time after lockdown.
It was claimed on social media that the man had attacked the store manager after becoming angry when trying to return a jacket.
Police said the incident could have been “so much worse” if it had not been for the bravery of members of the public.
Along with store staff, two men gave chase and restrained the alleged attacker until officers arrived.
Police have said the victims were taken to hospital and while their injuries are serious, they are not thought to be life-threatening.
A 57-year-old man was arrested at the scene on suspicion of attempted murder.
He was filmed by passers-by being led away by two police officers, still wearing his black face mask with his hands handcuffed behind him.
Police said they were considering his mental health as part of the investigation and that it was not terror related.
One social media post by a relative said the man’s mental health may have deteriorated because his mosque was closed during lockdown.
The poster, who said he was the man’s nephew, wrote: “He had severe depression for long as I can remember. We believe he may have relapsed and/or stopped taking his medication.”
A road worker, who did not wish to be named, witnessed two men stopping the man from escaping.
He said: “I saw the man run out of the store and he was being chased by two other men. They grabbed hold of him by his arm and held him against the wall.
“They held him until the police arrived, who then put him in handcuffs. I think they were shoppers who stopped him. I then saw one woman with bloodied bandage on her left arm. I didn’t see the other woman but I was told she had been stabbed in the neck.”
Tracy Bond, 45, who was working in the Salvation Army shop close by, said: “It was an Asian man who was arrested. He seemed pretty calm.”
Lancashire Police described the attack as an “isolated incident”.
Supt Stasia Osiowy said: “I would like to thank the public who acted without regard to their own safety. Without their brave actions this incident, while serious, could have been so much worse.”
An M&S spokesman said: “Our M&S colleague and the member of public who were injured are now in good care. We are supporting the police investigation.”