Police in southeastern Iran arrested an Afghan man suspected of stabbing 10 other farm laborers to death following a quarrel over land, Iranian state media reported Monday.

The official IRNA news agency said four Iranians and six Afghans were killed, and one farm worker was wounded in the rampage on Sunday and was in hospital. According to the report, the suspect was mentally unbalanced.

A decades-long drought in Iran has caused increased disputes over water resources and land with better access to water.

Violent acts have escalated in recent years in Iran as the country’s economic conditions deteriorate amid crushing American sanctions that helped spark soaring inflation and increasing unemployment.

In May, an employee fired from one of Iran’s largest state-owned financial conglomerates went on a shooting rampage at his former workplace in western Iran, killing three people and wounding five before turning the gun on himself.

In 2016, a 26-year-old man gunned down 10 relatives and wounded four others.