MARION, UTAH, JAN. 20 -- Sporadic gunfire from a band of polygamists today punctuated the fifth day of a standoff with authorities, and agents dropped a note into the group's compound by helicopter urging them to surrender.

Officers said they saw someone armed with a rifle come out of the house and pick up the note almost immediately after it was dropped late this afternoon.

The letter advised Addam Swapp and Vickie Singer "that we now have federal arrest warrants for them and . . . . explaining to them that it is the order of the court that they come out and surrender," said Nolan Douglas, an agent of the federal Bureau of Alcohol, Tobacco and Firearms.

The 15-member clan, including nine children under 18, is led by Swapp, 27, and Singer, 44, widow of polygamist John Singer. John Singer was slain by lawmen trying to arrest him in 1979 following an 18-day siege of the same 2 1/2-acre compound.

The current standoff with up to 100 officers began Saturday, hours after a nearby Mormon Church chapel was bombed. Swapp reportedly has claimed responsibility for the explosion, calling it divine revenge for Singer's death, and has refused since Saturday night to talk by telephone with police negotiators.

A federal grand jury in Salt Lake City today indicted Singer and Swapp, who is married to two of Singer's daughters, in the bombing and gunfire. The indictment superseded state charges filed earlier against the two, officials said.

The charges included malicious damage with an explosive, use and possession of a destructive device, and aiding and abetting in armed assaults on federal agents.

Authorities said they do not intend to storm the stronghold or return the shots fired out from the compound.

"We will not fire into the compound for fear of hurting children," FBI agent Dave Kohl said after 65 rounds were fired at police floodlights during a 14-hour period ending just before dawn.

Kohl said the shots appeared to be aimed at floodlights rather than police. He called the lights, which police set up Tuesday, "a defensive tactic . . . so we can have a view of anybody in the compound who would be moving toward the law enforcement positions."

The gunfire, believed to be from rifles, was not the only activity on the compound. Kohl said members of the band were seen running from building to building during the night, and lights, possibly from flashlights, were occasionally observed.

But he said there was no indication of surrender.

"That's all they'd have to do is walk out with their hands up," he said.