South Moluccan gunmen seized a government building and 50 to 60 hostages yesterday in a hail of bullets that left at least six persons injured. They vowed to kill the hostages if their demands were not met.

About 200 office workers fled, some leaping from windows and others shinnying down firehoses. One woman was feared dead.

The four to six raiders, members of a militant band that has terrorized the Netherlands in recent years, demanded freedom for 21 comrades in Dutch jails and a plane to fly all of them and hostages out of the country, Justice Ministry officials reported.

They said the terrorists, in a letter delivered to the Justice Ministry in The Hague, threatened to kill their prisoners unless the demands were met by a certain hour. The letter was signed by the South Moluccan Suicide Command.

Militants among the South Moluccan community in the Netherlands have made repeated terror strikes in recent years to dramatize their demands for Dutch help in winning independence from Indonesia for their Asian island homeland. The Moluccas and the rest of Indonesia were once a Dutch colony.

The area around Assen, 112 miles northeast of Amsterdam, has been the focus of the Moluccan terror campaign. Last spring gunmen seized 116 hostages in a train and schoolhouse and held out for 20 days before a military assault on the train ended the siege. Six terrorists and two hostages died.

A man who escaped said he saw one of the Moluccans push a woman clerk from a third-floor window. Officials said an injured person lying out of reach of rescuers in front of the building probably was that woman. They said they feared she was dead.

Police is armored ears quickly surrounded the building as the terrorists, said to be armed with pistols and at least one submachine gun, fired bursts of bullets from upper-floor windows.

There were about 250 employes in the building, headquarters of the Drenthe provincial government. Some were shot down from behind as they fled. One of the wounded was a schoolboy, shot as he walked down a street, officials said.

Police said yesterday's raid began at about 10 a.m. as the Drenthe provincial council was about to meet in the building. There were reports that at least two provincial legislators were among the hostages.

One Moluccand rode up in a taxi and dashed into the main entrance, pulled out a concealed submachine gun and opened fire, police said. The other gunmen ran in behind him.

One of those who escaped, clerk Leo Klok, 42, said he heard an uproar and "people were shouting, 'Get out of there! Escape!" He said he and two colleagues headed downstairs but suddenly found themselves facing a masked terrorist who opened fire but missed.

"We ran back upstairs and found a firehouse, which we unrolled and threw out of a window. We let ourselves down and then ran for our lives. The bullets were flying about our ears."

He said two people running with him were hit by gunfire but were not seriously wounded.

A police spokesman said the terrorists may have intended to kidnap Commissioner Tinneke Schilthuis, 56, the province's chief executive, but she escaped through a window of her ground-floor office.

Among the 21 Mollucans imprisoned for previous attacks are seven from the 1977 raids. The government of former prime minister Jopp den Uyl refused to give in to similar demands last year, insiting that the terrorists first release all hostages.

Last year's raids, during which the terrorists held 106 children hostage, stirred bitter hatred among the Dutch toward the Moluccan community.

About 40,000 South Moluccan immigrants lived in the Netherlands, 4,000 in the immediate vicinity of Assen. Many South Moluccans fought alongside the Dutch against Indonesian revolutionaries.