Gunmen attacked an Afghan family with acid after the parents refused to allow their daughter to marry a man they disapproved of, according to local officials.

The father was beaten, and then all members of the family (including all three daughters) had acid poured on them.

The attack occurred in the northern town of Kunduz and reflects a horrific custom whereby people (usually women and girls) are scarred by acid in retaliation for some perceived insult or slight.

Ghulam Mohammad Farhad, senior police detective for Kunduz, vowed to find the culprits.

We have started an investigation and those who have attacked them will be prosecuted, he told local reporters.

Reuters reported that a local man wanted the hand in marriage of 18-year-old Mumtaz, the oldest girl in the family. A few weeks ago, with her parents’ help, she refused his advances, and became engaged to someone else.

BBC reported that the jilted suitor was a member of a local militia known as the Arbakis and that he was much older than Mumtaz.

The Arbakis have reportedly been accused of committing a litany of crimes, including rape and extortion, according to BBC.

First they beat her father and then they attacked [us] with acid, Mumtaz's mother told Reuters.

The family is now at a hospital getting medical treatment for their injuries, according to Abdul Shokor Rahimi, chief of the Kunduz regional hospital.

The father and oldest daughter are in critical condition as they have been attacked all over the body, Rahimi said.

Their mother and two daughters who are 14 and 13 have some wounds only in hands and faces.

A family member told BBC: The man who did this is a criminal thug. There is no reason why we should be forced to accede to his demands. It is now a serious crime he has committed and the police must arrest him.''

Acid has been used for a number of other reasons other than romantic disappointment. In some of the more conservative parts of Afghanistan where the Taliban rules, girls attending school have had acid thrown on their faces and bodies.

In many cases, the victims are physically scarred for life, others are blinded, and some even die from the acid.

Acid attacks have also been reported over the years in Pakistan, Bangladesh and India.

In September of this year, seven women suffered acid attacks in the town of Faisalabad in Pakistan, according to the Express Tribune newspaper.