Relatives of a woman shot dead by a police officer in front of her three-year-old son are demanding authorities release the entire video footage of the incident.

Autumn Steele, 34, was fatally injured at her home in Burlington, Iowa, after being struck by bullets fired by officer Jesse Hill - who claims he was aiming at a her lunging dog.

A 12-second clip released by police shows the officer firing twice without warning, but not all the footage has been made available by officials.

Police claim the officer fired after the family’s German Shepherd, Sammy, pounced on his back and bit him - but that the bullets hit Ms Steele instead of her pet.

But regulators in Iowa say they will sue the police force after it again refused to release the remaining footage of the incident.

Local media said the Iowa Public Information Board voted to launch legal action against the Burlington Police Department and other agencies.

The board, which oversees the state’s open records laws, voted 4-3 to pursue charges against Iowa Department of Public Safety, the Iowa Division of Criminal Investigation, the Burlington Police Department and the Des Moines County Attorney.

“I’m, for one, uncomfortable with law enforcement determining what should and shouldn’t be released,” said Information Board member Bill Monroe, who voted in favor of the lawsuit, according to Iowa Public Radio.

Ms Steele was shot after officers responded to reports of a domestic abuse incident. Prosectors decided that the dog’s attack justified the officer’s actions and no charges were brought.

The footage released earlier this year does not show the family dog jumping on the officer, though it can he heard growling.

“Get your dog!” Mr Hill can be heard to yell.