TERROR: An armed and masked man broke into the halls of residence on Silverdale Rd.

A masked man armed with a gun is being hunted by Waikato Police after three home invasions in the Hamilton suburb of Hillcrest in two hours.

Police believed the same man might be responsible for all three incidents, Detective Sergeant Kristine Clarke said today.

The invasions were worrying, particularly due to their "possible sexual overtones," Ms Clarke told Radio NZ.

The first reported incident was about 3am Sunday, when a woman asleep with her partner in their Hillcrest Rd home woke to find a man standing over her bed and holding her hand.

The woman screamed and the intruder fled.

Twenty minutes later, a man arrived home at his Orelio St house to find an intruder who pointed a gun at him before fleeing, Ms Clarke said.

Then at about 4.15am, a young woman staying with a female friend in the University of Waikato halls of residence complex on Silverdale Rd woke up to find a man bending over her friend in an adjacent bed.

She challenged him and he threatened her with the firearm before running out the front door of the halls.

In each incident the offender was described to police as wearing a black or dark coloured hooded sweatshirt with a mask or bandanna partially covering his face.

Given the three incidents happened within about a kilometre of each other and the similarities of the victims' descriptions, police are not ruling out they were linked, Ms Clarke said.

Hamilton residents should make sure windows and doors were locked before going to bed, she said.