TOKYO--Japan is seeking to develop software to scan the Internet for signs of crime after authorities failed to spot enraged postings by a young man foretelling a stabbing spree, officials said Thursday.

Tomohiro Kato, 25, was arrested Sunday after ramming a truck into pedestrians in a crowded part of Tokyo and slashing people at random with a dagger, killing seven people and injuring 10 more.

Kato left hundreds of messages saying he felt lonely, ugly and angry. As he drove to Tokyo on Sunday morning, he sent more postings via his mobile phone spelling out his plans for a massacre, according to police.

"I'll crash my vehicle into people and if the vehicle becomes useless, I'll get out a knife. Goodbye everyone!" said one posting hours before the crime, as quoted by Japanese media.

Hiroya Masuda, minister of internal affairs and communications, told a cabinet meeting that the ministry would seek a budget to develop software that could catch messages such as those posted by Kato.

"We already have Internet software that detects certain words when somebody posts them online," ministry official Shingo Okamura told AFP.

"But just by searching information by keywords such as 'murder,' there is an enormous amount of information to screen," he said.

The proposed new software would aim to "catch when somebody's messages escalate to an alarming level in certain contexts."

Kato, a temporary worker at an auto factory, clung to his mobile telephone and the Internet as his main outlet for communication with the world, according to media accounts.

He was quoted as telling police that he became even more enraged when nobody seemed to notice his warnings that he was about to go on a rampage.

"I wish somebody could have stopped me," Kato tearfully told investigators, as quoted by media reports.