A police helicopter and dog unit were launched to trace a suspect who broke into a Horsham home and was shouted at by the person who lives there.
Emergency services were called to Paget Close at around 10.10pm on Monday night (November 25).
Sussex Police said the householder was alerted to the break-in after he heard a noise downstairs.
Officers believe the home may have been targeted for keys to a car which was parked outside.
A force spokesperson said: “Police were called to Paget Close at 10.07pm when someone fled from the house after they were shouted at when they were heard moving around in the ground floor of the property.
“It is not thought that anything was stolen.”
A police helicopter and dog unit were called in to search the area, including nearby fields, but no suspect was located.
PC Chris Jeacock, of Sussex Police, said: “This was obviously a very alarming experience, but it seems that the intruder was disturbed before they were able to steal anything.
“We are looking at the possibility that the target was the key to a car parked outside the house, but that is just one aspect of the investigation.”
He added: “We would like to speak to anyone who was in the area around 10pm on Monday evening, especially if they saw anyone hanging around or running from Paget Close.
“Please call us on 101 or email firstname.lastname@example.org quoting serial 1568 of 25/11/13.”
Alternatively you can contact charity Crimestoppers anonymously on 0800 555 111.