Three people died and more than 20 were injured when an explosion ripped through a building in western Japan where an office siege was underway.
Scenes of the blast were captured on television
A 52-year-old man, said to be a disgruntled office worker, was reportedly armed with a knife and a bow and arrow when he went into the office of courier firm Keikyubin, in the city of Nagoya.
Witnesses said he took his boss and seven other employees hostage, demanding three months' back pay.
He then doused the area with kerosene, and police were trying to negotiate with him when the blast happened at 1pm local time (0400 GMT).
Police said the man, Noboru Beppu, had threatened to set himself on fire if he saw "even one policeman''.
Television cameras caught the dramatic scenes as windows were blown out, showering the street with glass and documents.
Police officials said the three victims were the hostage-taker, the manager of the office and a policeman.
Several other police personnel, as well as journalists, firefighters and members of the public were among the injured.
"The blinds were sucked in, and the entire floor just
turned red," said Koji Hirano, a banker who was walking
past at the time of the blast.
"Glass was raining down everywhere," he told the Associated Press news agency.
"It was unbelievable," said Kanta Hisaizumi, an employee
at the next-door karaoke parlour.
"There was this boom and then black smoke starting pouring out," he said.
It took firefighters two hours to bring the blaze under control.
The contract worker had walked into the office earlier on Tuesday, wheeling a large drum, which he kicked over and set alight while police were negotiating with him, says the BBC's Jonathan Head in Tokyo.
The death toll could have been worse if seven of the hostages had not previously been released.
Financial disputes are thought to have been behind two hostage-taking incidents in Japan last December - one at a building contractor's office and the other at a bank.