The 25-year-old victim, who has not been formally identified, was found by police in Brayfield Road, Liverpool, at about 10.10pm on Tuesday night.
Officers were called to the area in Anfield after a member of the public reported hearing gunshots and seeing a group of men acting suspiciously.
A spokesman for Merseyside Police said the victim died from a single gunshot wound to his head.
Forensic examinations were taking place at the scene yesterday and a Ford Mondeo recovered nearby is being studied. Police are also carrying out house-to-house inquiries and examining CCTV from shops and businesses in the area.
A police spokeswoman said officers were keeping an open mind about the motive for the attack.
She added: “The circumstances of his death are now being investigated by the force’s major incident team and detectives are appealing for anyone in the Brayfield Road area who saw or heard anything suspicious on Tuesday night to contact police.
“The victim’s family have been notified and are receiving support from specially trained family liaison officers.”
Residents in the area expressed shock at what had happened but said the street had been the scene of another shooting around two months ago when a window was shot through.
A 77-year-old man, who has lived in the street for 45 years, said: “It’s very scary. It’s normally very quiet around here.”
A woman aged 29, who asked not to be named, added: “We are shocked. We saw all the lights out of the window. There were about nine police cars and three ambulances.
“I have got a little boy and I was putting him to bed at the time and you just don’t expect anything like this to happen right outside your front door.”