Police arrested a 19-year-old man Monday for allegedly threatening on the Internet to go on a stabbing spree at Tokyo Disneyland.

The message, posted on a Web site by someone using a cell phone on June 15, came a week after a man posted similar warnings before killing seven people in a downtown Tokyo knifing rampage. Authorities were also searching for a woman suspected of wounding three people in a knifing incident Sunday.

Since the deadly stabbing attack in early June, police have arrested several people for allegedly using the Internet to make chillingly specific threats of violence.

"I will go to Disneyland to stab visitors to death," the 19-year-old wrote, according to a police official in Chiba, the suburban area where the amusement park is located.

The suspect's name was not released because he is below the age of 20 -- a minor under Japanese law.

Investigators have found no evidence that he was preparing to carry out a real assault, the official said on condition of anonymity, citing department policy.

The arrest on Monday coincided with a search for a woman suspected of stabbing three people in the arm at a crowded train station in the western city of Osaka.

On Sunday police released security camera footage showing a middle-aged woman in a black dress making what local news reports interpreted as stabbing motions with her left hand. No knife was visible in the video and a large sun hat obscured the woman's face.

She was suspected of stabbing three women from behind. The victims suffered light injuries, according to a police spokesman who requested anonymity because he was not authorized to speak to media.

Japan has been on alert for copycat crimes in the wake of the June 8 mass stabbing that killed seven people and wounded 10 others. The suspect in that attack, 25-year-old factory worker Tomohiro Kato, apparently posted hundreds of threatening messages to the Internet before the incident, with the last one sent just 20 minutes before the violence started.