A Saudi Arabian school teacher shot and killed six of his colleagues Thursday, Saudi news outlet al-Arabiya reported. At least two more people were wounded in the attack, and the suspect is in custody.

The attack occurred in the Jizan region of the country, just north of Yemen, the report said.  The shooting may have been motivated by interpersonal problems between the shooter and his colleagues. Saudi Arabia has been involved in the ongoing conflict in Yemen though Saudi Interior Ministry spokesman Gen. Mansour Turki said police were treating the attack as a criminal investigation, Reuters reported.

While mass shootings are very rare in Saudi Arabia, 1,829 homicides were committed in 2012, according to data from the United Nations Office on Drugs and Crime. With the nation’s population around 28.2 million at the time, that makes the homicide rate around 6.5 people per 100,000. By comparison, the United States saw 14,827 deaths with a rate of 4.7 per 100,000, in the same period.

Saudi Arabia has faced recent attacks from the terror organization known as the Islamic State group. The militants in this group, also known as ISIS, want to impose Islamic law across Iraq and Syria, and they have targeted countries that participated in airstrikes against them, including Saudi Arabia. The nation also has a large Shiite population the Sunni militant group has said needs to be destroyed.

Assailants attacked a Shiite mosque in eastern Saudi Arabia in January, opening fire on worshippers and using a suicide bomb in an incident that left four dead and 18 wounded. While authorities could not immediately determine who was responsible for the attack, ISIS claimed responsibility and the attack bore the hallmarks of many previous suicide bombings the group had carried out in the region.