CHP Officer Mike Wright said Loaiza was driving his Ferrari in excess of
120 mph about 3:30 a.m. Wednesday on northbound Interstate 238 near San Lorenzo when he was stopped.
Loaiza was arrested on suspicion of reckless driving and driving under the influence when he failed a Breathalyzer test, Wright said.
Loaiza who signed a three-year, $21million contract with the A's in November spent the night at North County jail and will likely face steep fines and probation because of the combined charges, Wright said.
"He is very fortunate nobody got hurt,"
A's Assistant General Manager David Forst said the A's are aware of the incident.
"It's an ongoing legal matter," Forst said. "We'll have no further comment."
Loaiza is still scheduled to start today's series finale against the Seattle Mariners. Loaiza left before Wednesday's game concluded, which Forst said was common for the pitcher scheduled to start the next day.
The 10-year veteran signed with Oakland as a free agent after playing with the Washington Nationals in 2005.