BEIJING - A man in China's far west has been arrested in the deaths of five children, who were apparently suffocated and stabbed after being left alone in their grandparents' home, local media and a police official said Tuesday.

The man was arrested Monday in the city of Wusu in the Xinjiang region, said the Wusu police commissioner, who would give only his surname, Yang.

He said the motive for the killings was under investigation and would not release any other details.

The children, four boys and a girl aged from 2 to 13, were left alone on Sunday while their grandparents went to a market three kilometers (two miles) away to buy food, according to a report by the local Metropolitan Consumer Morning Post posted on the news Web site Sina.com.

Their bodies were found a few hours later, the newspaper said.

Two were bloody and appeared to have been stabbed, while the other three did not have any apparent injuries and were likely suffocated, the newspaper said.

The grandparents had been taking care of the children because their parents were working out of town.