Police are searching for two people after a man was killed in a "violent" and "targeted" attack on a quiet suburban street in inner-city Sydney.

Key points: Police believe the attack was targeted and are searching for a man and a woman

Police believe the attack was targeted and are searching for a man and a woman The manhunt involves a helicopter and the dog squad

The manhunt involves a helicopter and the dog squad Some residents in Forest Lodge have been stopped from returning to their houses

The 30-year-old man was found dead with head injuries in the middle of the street.

The body was lying at the intersection of Hereford Street and Minogue Crescent at Forest Lodge, a suburb in inner-city Sydney and just 100 metres away from a local primary school.

Police believe the attack was targeted and a searching for a man and a woman.

A gun was found nearby, however police are yet to confirm how the man died.

NSW Police acting Superintendent Sam Crisafulli said there were several residents in their homes when the "violent attack" occurred.

"We've spoken to a number of witnesses who tell us shortly before we were called a man and a woman were in an altercation with another man," Superintendent Crisafulli said.

"It was a violent attack with very, very serious consequences."

Police blocked off the street in Forest Lodge after a man was found dead. ( ABC News: Jennine Khalik )

About two hours after the attack, the riot squad entered a home on Hereford Street.

Superintendent Sam Crisafulli said the Hereford Street property had been secured as a crime scene.

He said police believed the man and woman had left the area but sniffer dogs and police were still searching for evidence.

Police said the man was believed to be in his 20s. ( AAP: Dean Lewins )

Local Dominic Johnson, whose wife was inside their house when police arrived, said she looked outside and saw a body on the street.

"She was shocked," he said. "It's a really lovely neighbourhood.

"It's concerning. We think it's a pretty safe place. I've got two daughters."

He has spoken to his wife on the phone, and said he was not allowed to go back into the area.

Wally Mason, who also lives in the area, was walking his dog at the time.

"I know everyone says something like, 'It's always been quiet'," he said. "I don't ever recall a murder though."

The area where the body was found is close to a local primary school.

Police are appealing for information.