Chinese authorities say a man who attacked students with a knife outside an elementary school in central Henan province last week may have been influenced by ancient prophecies predicting the end of the world.

Police say Min Yongjun rushed into the school Friday with a kitchen knife and allegedly slashed 23 students and an elderly villager before being subdued by teachers and police. None of the students were injured seriously.

The official Xinhua news agency said an initial investigation found Min “had been strongly psychologically affected by rumors of the upcoming end of the world by ancient prophecy.” His specific motives are not known.

Some say the ancient Mayan calendar predicts the world will end on Friday, December 21.

Security at Chinese schools has been increased in recent years following a series of violent attacks on students, mostly involving mentally unstable young men.

Most of the attackers have used knives, hammers, or meat cleavers. Some observers say this is because China has tough laws restricting private ownership of guns.

Friday's incident came just hours before U.S. gunman Adam Lanza burst into an elementary school in Newtown, Connecticut, with a rifle and two handguns, in an attack that left 20 children and six adults dead.

It was the second-worst school shooting in U.S. history.