Police say the suspects took a small amount of marijuana and some cash, before leaving the clinic in a tan late-model Nissan Titan pick-up truck.
"They were very calm and meticulous and there was no panic on their part," said Det. John Doerbecker of the Los Angeles Police Department.
The victims are still in intensive care at a hospital.
The suspects could face robbery and attempted murder charges.
Anyone with information on their whereabouts is urged to call Los Angeles police at (877) 527-3247.