THREE people have been arrested as police continue their investigation into an armed robbery at an East Yorkshire post office.

A large sum of cash was stolen when a man in a balaclava threatened staff at Hornsea Post Office in Cliff Road, Hornsea, at about 6.45pm on Monday, January 27.

Humberside Police said a 54-year-old man, an 18-year-old man and a 53-year-old woman, who are all from the Hornsea area, have been arrested.