PENGYANG -- Police explained on Saturday how marital dispute has led a man to murder his wife and six other members of their family in Northwest China's Ningxia Hui autonomous region earlier this week.

After the killings on Monday, suspect Ma Yongdong was arrested on Friday evening in the city of Wuzhong and sent to Pengyang county, where the tragedy happened, at around noon on Saturday, sources with the public security bureau of Pengyang said at a press briefing.

Ma confessed to the murders of his seven family members including his pregnant wife and two young nieces, according to the police.

They said Ma killed his wife, his parents in-law, grandparents in-law and two nieces aged three and one in their home in Wengou village of Pengyang on the night of Oct 14 after he had an argument with his wife that afternoon.

Villagers said Ma had quarreled with his wife Lan Xiuying, who is nicknamed Lan Xiaohong, frequently in recent days as Lan was seeking a divorce. They said Ma also had frictions with his parents in-law.

Lan's relatives told Xinhua that Ma had threatened Lan and said, "If you insist on divorcing me, I will kill your family."

Ma, 24, only received junior middle school education. He and Lan got married about four years ago. They had marital conflicts for Ma was addicted to gambling and even lost his job at a local coal mine company, according to Lan's relatives.

Further investigation into the case is under way.