A pregnant woman in the United States of America has been shot dead by a gunman who was driving a car.

She was on a party bus outside the Milwaukee venue when the incident happened.

The woman identified as Annie Sandifer was rushed to hospital after being shot at 5 or 6 times, the Times Magazine has reported.

She was pronounced dead at the St Joseph Ascension Hospital.

Doctors, however, managed to deliver her baby through cesarean section.

It was delivered prematurely, reportrs indicate.

Relatives of the woman reacted with shock to the grim development.

“She did everything as a mother should,” said her cousin, Kisha Ducksworth as quoted by the Washington Post. “She went out of her way for her kids,” she added.

Law enforcement officers say that they are yet to arrest the culprit let alone establish the motive of the shooting.

A manhunt has been launched.

Friends and relatives held a candle-lit vigil in honour of Annie Sandifer.

The grim development comes as America grapples with the vexed issue of mass shootings.

Americans strongly disagree on how to go about tackling the issue.

The strong gun lobby, the National Rifle Association (NRA) has rejected any attempts to take guns away from civilian hands.