Rescuers searched late Wednesday for the bodies of three young children who were reportedly tossed into San Francisco Bay near a popular waterfront attraction, authorities said.

A man called 911 at 5:30 p.m. to report that the children had been dropped from a pier into the chilly water, said Fire Chief Joanne Hayes-White. The case was being investigated as a homicide.

The children were believed to be under age 10, said Police Chief Heather Fong.

As darkness fell, a small inflatable Coast Guard boat hugged the waterfront as rescuers with flashlights looked under the pier. Larger Coast Guard and city police boats searched the water with high-powered lights.

"The temperature in the water is rather cold," Hayes-White said. "It's windy. I'm understanding there's a strong northerly ebb tide. It would make a rescue situation very difficult. Very soon it would most likely be a recovery effort."

Mayor Gavin Newsom arrived for a briefing from officials at the scene. He would only tell reporters, "I'm sick to my stomach."

The incident happened at Pier 7 in the Embarcadero area, which draws tourists to the historic Ferry Building within view of the landmark Transamerica pyramid.

The wooden pier, lined with a wrought-iron fence, is several hundred feet long and extends into water 35 feet deep.