TOKYO, Sept. 16 (Xinhuanet) -- A man armed with a knife took eight people hostage at a courier company in Japan's central city of Nagoya on Tuesday morning, demanding unpaid wages and spraying liquid around before the office blew up.

　　The massive explosion rocked the fourth-floor office of Nagoya-based Keikyubin Co. at 1:10 p.m. (0410 GMT), only 10 minutes after seven of the hostages were freed, Japan's national police agency said.

　　According to the police, the entire floor was engulfed in flames and black smoke was billowing from the shattered office. Fire engines, which had been rushed to the scene, immediately started pumping water into the building.

　　The suspect, identified as a 52-year old local, was demanding unpaid wages from July to September, the police said.

　　It is unknown whether he or the remaining hostage survived the blast.

　　There were 31 staff in the office at the beginning of the incident, but the hostage-taker released the others before taking the eight remaining staff captive. Enditem