Billboard Crowds Seen as a Hazard : Curiosity: Nightly throng seeking to view ‘apparition’ of slain girl swells to 10,000.

A festive crowd of more than 10,000 gathered here Friday night for a chance to see the purportedly miraculous image of a slain girl appearing on a blank, white billboard, prompting concern by police that the nightly event is turning into a public safety hazard.

The mystic atmosphere that has surrounded the “apparition” was heightened shortly before 9 p.m. when the three 400-watt light bulbs illuminating the base of the billboard suddenly went dark. Five minutes later, they began flickering back on, one by one.

“Spooky! There really is something there,” one elderly woman said as she leaned on a cane.

Believers say the billboard displays the face of Laura Arroyo, a 9-year-old San Diego girl who was found slain last month after being abducted from her home about two miles away.

Despite official assurances that what they see is nothing more than light and shadow against a white backdrop, many onlookers believe that the dead girl is attempting to provide a clue leading to her assailant in the unsolved killing.

“Right now, we’re concerned about the public safety,” said Chula Vista Police Lt. Merlin Wilson, adding that the nightly traffic jams are straining police resources. “I’m afraid that it’s just a matter of time before we have some kind of an incident out there, before someone gets run over or something.”

Thousands had gathered at the scene before dusk. Those wanting a close-up view without walking paid $3 to park in a field near the billboard.

Many brought cameras on tripods; others carried binoculars. And thousands continued to see what they said were one or more faces, despite the fact the sign company changed the wattage of light bulbs at the base in the hope that the interplay of light and shadows would be altered.

“I could see two faces on the left and the right, the eyes looking downward,” said Ferdinand Cosico, who brought his wife, Sandra, and 3-year-old son, J.R., from their nearby home.

His wife said that she could see “only one face, sort of in the middle. I think maybe all of this is just a play of the light.”

Andrew Datan from Del Mar and his co-worker, Barry Galviso, had been in the South Bay during the day selling bottled water. “To be honest, I don’t see anything, at least not yet, “ Datan said. “We came down here like everybody else. You hear about these ghost stories and you never know.”

Police said they had no idea why the lights went out Friday night.