The standoff, which forced the evacuation of the surrounding block and a nearby girl's school, lasted less than an hour.
The smoky fire caused only minor damage to the twin-spired Cathedral of St. John the Baptist, which dates to 1873 and is the site of the Mass that kicks off this city's annual St. Patrick's Day festivities.
The heavyset, blond man, who was not identified, entered the sanctuary shortly after morning Mass ended about 9 a.m. Receptionist Peggy Baker said she approached him when she saw him walk up to the altar.
``He told me to stand back, he had lighter fluid,'' Baker said. ``He threw it on a chair and started lighting a cushion. I told him he can't do that. ... He told me to stand back and pointed the gun at me.''
Savannah Archdiocese spokeswoman Barbara King said a monsignor noticed the man on a security camera setting fire to the altar and ran inside the sanctuary yelling at him to put the fire out. She said he set fire to the bishop's chair and another chair where priests sit.
The man was arrested less than an hour later, and King said he was so taken surprise by officers that he left the gun laying on the altar.
King said the church, which was rebuilt after a fire more than a century ago, underwent a $10 million restoration in 2000 and remains a popular tourist stop. The flames were contained only to the altar but smoke damage may be more extensive, she said.
