Jiang Zhaopeng, an 18-year-old medical student, faced a life-or-death test on Saturday — not in an exam hall, but in the backseat of a car, where he performed life-saving CPR on a classmate who went into cardiac arrest.

Jiang and his classmate were heading to take the spring college entrance exam when the emergency unfolded unexpectedly. Both attend Shandong City Service Technician College in Yantai, a coastal city in Shandong province.

At about 8:10 am, the two boarded a ride-hailing car bound for the testing site. Just a minute later, Jiang's classmate collapsed onto his lap, showing signs of a heart attack, seizure and cardiac arrest.

"I thought he was just tired at first," Jiang said. But then the classmate began gasping and convulsing, violently kicking the front seat before suddenly going limp. He soon stopped breathing.

Drawing on first aid skills learned in school, Jiang quickly sprang into action. He laid his classmate flat and began performing cardiopulmonary resuscitation, alternating with rescue breathing.

"Go to the hospital," Jiang told the driver, Wang Tao.

Wang alerted the local traffic police and sped to the hospital, running six red lights and arriving in just seven minutes — half the usual time.

Only after ensuring his classmate was under professional care did Jiang notify school officials about the emergency situation. He then rushed to the exam site, but arrived too late to take the 9 am Chinese language test.

Doctors later confirmed that Jiang's classmate would recover without brain damage.

"The first four minutes of CPR in the car were absolutely vital," said Yang Haiyan, head of the emergency department at the East Hospital of Yantaishan Hospital.

"The patient received 29 minutes of resuscitation in the hospital and eight defibrillations before his heartbeat stabilized at 8:50 am," Yang said.

Though he missed the exam, Jiang said he has no regrets about his decision.

"Exams can be retaken, but a life cannot," he said.