Manhunt Underway After Teens Shot Dead In Bedroom

A crime scene has been established in Sydney's north-west and police are seeking a person of interest.

A police manhunt is underway after two teenagers were shot dead in a suspected domestic violence-related incident in Sydney.

Authorities were called to the home on Hull Road in West Pennant Hills at around 5.20pm on reports of gunshots.

When officers arrived, they found a teenage boy and girl deceased in a bedroom, in what an officer described as a "horrific scene".

"When ambulance paramedics arrived on scene this afternoon we were confronted with an extremely distressing and stressful situation," NSW Ambulance Inspector Kevin McSweeney told reporters.

"We found two teenagers unfortunately deceased in their bedroom, and unfortunately at that time there was nothing we could do to help them."

A woman in her 30's, who police understand may be the mother of the teens, is currently being treated for shock. She arrived at the scene shortly after police.

NSW Police confirmed a person of interest has been identified and early investigations suggest the matter is related to domestic violence.

A fleet of ambulances and police cars attended the scene in West Pennant Hills.

"At this stage the person of interest we are looking for is still at large, but we believe this to be a targeted incident and that there are no risks to the community at this time," Acting Assistant Commissioner Brett McFadden told reporters.

"There's no other way you can describe this, it's an absolutely horrific incident to unfold."

Police have confirmed they are searching for a person of interest.

A crime scene has been established on Hull Road, 20km northwest of the city's CBD.

Ryde detectives are being assisted by detectives from the State Crime Command’s Homicide Squad.

With AAP.