Update 11:00 p.m.: Authorities said late Friday night that after tracking the stolen sailboat for most of the day, they decided to confront the vessel when it took an unexpected turn south after reaching Monterey Bay. Coast Guard and FBI approached via boat and Maffei cooperated, allowing them to board the yacht.
Before a fisherman notified the Coast Guard that he spotted the vessel 50 miles off the coast of Half Moon Bay early Friday morning, authorities were reportedly conducting air searches in the region of the Sacramento Delta.
At around 10 a.m., the US Coast Guard spotted the vessel. According to one police officer at the pier late Friday night, Maffei did look up to a Coast Guard aircraft at one point during the day and wave.
Late Friday night, the children's mother arrived at the Monterey pier and was reunited with them while they were checked out by peramedics.
The two young South San Francisco children who were allegedly on Tuesday have been rescued by the US Coast Guard off the coast of the Monterey Peninsula.
According to the Coast Guard, the sailboat was apprehended this evening and the children are unharmed.
Christopher Maffei, the children's father, surrendered without incident in sailing waters off the peninsula shortly before 8 p.m. Friday, Coast Guard spokesman Thomas McKenzie said. He said the children would be checked out by medical personnel, but anticipated they would return home shortly.
Early Friday morning, a commercial fisherman saw the vessel 50 miles off the coast of Pillar Point in Half Moon Bay, and had since traveled south toward Monterey.
Maffei is reported to have left South San Francisco Tuesday with the kids before stealing a yacht at Ballena Isle Marina in Alameda.
South San Francisco Police worked with county, state, and federal agencies during the investigation.
Bay City News and Sara Rubin in Monterey contributed to this report.