Four masked men allegedly threatened a woman and attacked her male friend at a property in Grimsby.
One man has already been arrested in connection with the incident, which took place at a property on Donnington Street on March 7 at around 7pm, and police are still on the look out for the other three.
A woman in the property was threatened by the men after they entered her home wearing black and white masks and hooded tops.
Her male friend was assaulted. He sustained injuries to his head, Humberside Police said.
The suspects reportedly fled in a red car thought to be an Audi.
Police believe it was an isolated incident and anyone with any information or who saw something should contact police on 101 quoting log 484 of March 7.