One of the teenagers from the IES Carolina Corona college of Almendralejo is reported to be in critical condition.
The three other students have less life-threatening injuries but are undergoing tests at a local hospital, online daily Hoy reported.
The accident, which took place around 12.45pm on Monday, has been described by police as “a lapse in concentration by a learner driver”.
The woman in question is thought to have “driven in the wrong lane, then onto the curb and ended up hitting a tree”.
Almendrajelo is a town in the region of Extremedura in western Spain, with a population of approximately 35,000.
Una conductora novel ha atropellado a cuatro alumnos de primero de ESO del 'Carolina Coronado', sobre las 12.45 horas, en la Vereda Corona. La mujer se habría despistado al volante, invadiendo el carril contrario y subiéndose a la acera. Hay un herido grave. pic.twitter.com/7aHOvkm9Bo— Cope Almendralejo (@copealmendralej) March 12, 2018