Saudi police and members of the feared religious police are responsible for the death of a man and the injury of his pregnant wife and two children in a car chase, said an inquiry published on Wednesday.
"A police patrol car and a religious police patrol car are responsible for the accident", said the report, adding that "both sides failed to follow orders and instructions that ban chases."
The incident involved an argument between the family and a member of the religious police who complained their car stereo was too loud.
The victim, 34-year-old Abdulrahman al-Ghamidi, refused to follow orders to turn down the music and drove off, prompting the chase.
The religious police sometimes use unmarked cars to chase those they suspect of violating Islamic sharia law, such as unmarried couples.
Four members of the Commission for the Promotion of Virtue and Prevention of Vice were arrested after being interrogated on Sunday over the chase, Okaz daily reported.
They will be charged with "abusing power, chasing a man with his family while ignoring instructions given to members of the committee completely banning chases," the daily quoted a religious police official as saying.
Prince Mashari bin Saud bin Abdul Aziz, governor of southwest Al-Baha region where the incident, occurred has pledged to punish all those responsible for the accident.
Relatively moderate Sheikh Abdullatiff Abdel Aziz al-Sheikh, appointed in January as the new chief of the religious police, has raised hopes that a more lenient force will ease draconian social constraints in the Islamic country.
Two weeks into his post, Sheikh banned volunteers from serving in the commission which enforces the kingdom's strict Islamic rules.
And in April he went further, prohibiting the religious police from "harassing people" and threatening "decisive measures against violators."
The religious police prevent women from driving, require them to be covered from head to foot in black, ban public entertainment and force all businesses, from supermarkets to petrol stations, to close for prayers five times a day.