Twenty men and four women landed on the beach in a 25-foot-long panga boat, an open-air wooden fishing boat with a single outboard engine. The incident occurred at 4:30 a.m.
Panga boats have been involved in drug runs into California in the past, but authorities say there were no narcotics found Thursday.
All 24 people were taken into custody.
The U.S. Customs and Border Protection agency was investigating the incident.