Fifteen people were killed in China on the night of the Lunar New Year in two family tragedies, after one man started a fire and another went on a knife rampage.

As people celebrated to welcome in the Year of the Pig Monday night, a man surnamed Lu set fire to the home of his brother in the northern province of Shaanxi, killing seven, according to police in the town of Baoji.

The brother, his wife, their fathers and their three children died in the blaze, police said on the Twitter-like Weibo platform.

A few hours after the incident police arrested the suspect, who had just tried to kill himself.

During the same night, a man surnamed Guo, who suspected his wife of adultery, stabbed eight people to death and injured seven in a village in the northwest province of Gansu, according to police in the commune of Baiyin.

The man, aged 49, has been arrested. The identities of the victims have not been released.

Knife attacks are common in China, where the carrying of firearms is strictly regulated.

Violent crime has been on the rise as the economy has boomed in recent decades and the gap between rich and poor has widened rapidly.

Studies have also described a rise in the prevalence of mental disorders, some of them linked to stress as the pace of life becomes faster and support systems wither.