At approx 4.45 pm on Saturday a man went into the Cash-in pawnbrokers on Victoria Street and ran out with a £1,500 ring.
He asked the female shop assistant to show him the ring from the front window and in a split second took the ring and fled.
The manager and his assistant chased the thief along Victoria Street. When he got near Freshney Place he was apprehended by them. They the wrestled him to the ground and tried to retract the ring.
He refused and threatened to kill them. It is believed that two other accomplices intervened and pulled them off the thief. Then thief and his accomplices then all ran off, the manager and his assistant managed to get the ring of him.
It has been the second time this year that the Cash-In staff have attempted to apprehend thieves. The manager stopped an ax-wielding jewellery thief who was attempting to get away with £15,000 from the shop.
The suspect has been described as a man in his 20s about 6ft tall, slim build with very short brown hair. He was wearing a black Adidas tracksuit.
Anyone who has any information about the theft or witnessed the men running away from the store. Should contact Humberside Police on the non-emergency number 101 quoting ref 16/12817/19.