"We have three vessels that have been on the scene searching the waters
and, now that we have sunlight, we've added a helicopter to the effort," said Lt. Josh Nelson of the Coast Guard.
The search has not turned up any survivors or any additional wreckage since some debris that included pieces of aluminum and carpeting was found about 30 miles off Oceanside, some three hours after the crash, Nelson said.
"We have some leads on planes that may have gone down, but so far we don't have any confirmation," he said. "I expect that some decisions will be made in the next few hours as to whether to continue or suspend the search."
The plane may have taken off from Montgomery Field in the Kearny Mesa area.
Some boaters who reported the plane hitting the water about 2 p.m. told the Coast Guard they were 20-30 minutes away from the impact site and found an oil slick when they got there.