The accident happened around 5:30p.m. on eastbound Oceanside Boulevard, just east of El Camino Real, according to Oceanside police.
Investigators said a blue Chevrolet Impala was driving in the center island and suddenly lurched out into oncoming traffic.
Two people, including the driver of the Impala, were airlifted to the Scripps Memorial in La Jolla where they underwent surgery.
Police said speed was not the cause of the accident but have yet to rule out texting and driving or driving under the influence.
Check back for updates on this developing story.