A detective was arrested yesterday after allegedly pulling out his service revolver during an argument with a Yau Ma Tei restaurant owner, who refused to give a discount to him and his friends. The proprietor of the Nathan Road restaurant said that when the group called for the bill, one claimed to be a police detective and took out his revolver, while another said he was a member of a triad gang and asked for a 'good discount'. When the proprietor refused, the group paid and left. However, as the owner was leaving his restaurant about 4am, he was allegedly attacked by about 20 men, who fled before police arrived. He was admitted to Queen Elizabeth Hospital with head and arm injuries. Kowloon West regional crime unit officers later arrested a detective attached to Shamshuipo station.