A search is underway for a girl who was swept away in the ocean in Southern California, officials said.

The incident unfolded at about 7:30 p.m. on Tuesday near Treasure Island Beach in Laguna Beach, city officials said. The girl was with her mother and a sibling near the shoreline when they were swept into the ocean by powerful water conditions, city officials said.

Bystanders ran into the water and were able to rescue the mother and one of her children, but the other child remains missing, officials said.

The search and recovery effort is ongoing on Wednesday. The Laguna Beach Marine Safety Department has expanded the search to areas beyond where the girl was last seen based on “ocean conditions, currents, wave action, and drift modeling,” city officials said in a statement.

“Ocean conditions remain challenging, with large surf and strong currents affecting the coastline. Large surf is forecast to continue through the remainder of the week,” officials said. “Search managers continue to evaluate these conditions and adjust operational tactics accordingly. Anyone who spots anything unusual along the coastline should immediately call 911.”