An explosive device brought into the main railroad station of the Chinese capital yesterday by "an unknown person" resulted in nine deaths and hospitalization of 81, China's official news agency said tonight.

It was the first such incident reported in four years in what has appeared to be a relatively terrorist-free society for a decade. The report said high-ranking government ministers, the mayor and an Army general rushed to the station after the blast yesterday evening. The initial official statement, by the Foreign Ministry, had referred to the "accident" and had given no details.

A 1976 explosions of a bomb brought into a Chinese Army guardhouse outside the Soviet Embassy here has to this day never been explained. Tonight's official New China News Agency report again gave no reasons for yesterday's blast and did not call it the work of a terrorist.

The news agency said, "One man died on the spot" and eight men and women died later. Of the 81 injured, "two are in critical condition," the agency said.

Known incidents of terrorism have been rare in China in recent years, and no individual or group is known to have claimed responsibility for the latest explosion. The 1976 blast killed the Chinese man who brought the bomb into the guardhouse as well as killing nearby Chinese soldiers. Residents of the central Chinese province of Henau have reported to visitors that an Albanian diplomat was murdered these in the mid-1970s by a Chinese group, but the incident has never been officially confirmed.

China has apeared in the last decade as a largely homogeneous society with few of the ethnic and religious tensions that have led to terrorism else-where in the world. Clashes between organized political factions and political barassment of senior officials caused thousands of deaths here in the 1960s, however. In the last two years China has reported unusual outbreaks of crime and some public political protests, either calling for more government democracy or for redress of many personal grievances left over from the tumultous 1960s.

China has several different ethnic minorities living in border areas, and the Chinese have sometimes suggested that saboteurs from anticommunist Taiwan ar operating here, but there has been little sign of any overt violence from these groups in the last several years.

Security appeared somewhat tighter than usual at the cavernous railway station today. Soldiers seemed to be patrolling parts of the complex, and one pair of troops wearing pistols stood near the explosion site. The blast, which occurred near the top of an unused escalator, appeared to have done little damage. Passersby stared at a few scratches and small holes in the walls and ceiling.

According to the officials news agency report, "Public security officers investigating the explosion said that the blast had been caused by an explosive charge brought into the railway station by an unknown person." A chinese spectator yesterday said several soldiers were among those injured and speculated that they might been carrying explosives, but the news agency statement said nothing about this.

"The station was immediately cordoned off as doctors tended injured and dying," the agency said. "Ambulances later took the casualties to hospitals." A Chinese who arrived at a nearby hospital for an appointment two hours after the explosion was turned away because of the crush of victims needing treatment.

The agency said several high officials rushed to the scene of the explosion, including Public Security Minister Zhao Cangbi, Railway Minister Guo Weichen, Peking Mayor Lin Hujia, and Peking military commander Gen. Qin Jiwei.