RENO, Nev. - A dust storm chased away some participants from the counterculture Burning Man festival before its traditional climax Saturday night on the northern Nevada desert, authorities said.

Roger Farschon, incident commander for the federal Bureau of Land Management, said the dust storm on the Black Rock Desert about 110 miles north of Reno began early Saturday afternoon and continued into the evening.

"We are in (a) total whiteout," he wrote by e-mail. "A similar cold front caused a major dust event on Monday. The rest of the event has been relatively dust-free."

The annual celebration of radical self-expression was scheduled to climax Saturday night with the torching of its 40-foot signature effigy.

The crowd on Saturday morning reached a record 49,599, up from 47,097 last year, authorities reported.

Farschon said he was unaware of any fatalities or major arrests during the weeklong event leading up to Labor Day.

"Overall, the event is going smoothly with no major problems," he wrote. "Medical cases are very consistent with last year with daily patient loads of 0.5 to 0.7 percent of the population."

The BLM had made six arrests and issued 129 citations to participants through early Saturday morning, many for drug violations.

Burning Man, an eclectic art, music and performance festival, began in 1986 at San Francisco's Baker Beach and was moved to the Black Rock Desert in 1990.