The problem was reported at 10:47 a.m., and the pilot made the emergency landing at 11:05 a.m., airport spokeswoman Marilyn Sandifur said.
Emergency personnel were standing by during the landing, but no injuries were reported, Sandifur said. After landing, crews inspected the Boeing 737 and found a minor hydraulic fluid leak.
The plane arrived at the gate at 11:33 a.m., and all passengers were allowed to exit. An estimated 134 people were on board Flight 220 from San Diego to Oakland.
Some witnesses reported seeing smoke coming from the plane, which was likely due to the hydraulics fluid heating up and smoking after it leaked onto the landing gear, Sandifur said.