A paramedic in Detroit became both the caregiver and the patient last Friday when he went into cardiac arrest while saving the life of a man in cardiac arrest.

Joseph Hardman, an 11-year-veteran of Detroit's EMS unit, had just started his shift around 7 a.m. when the first call of the morning sent him and his partner out to help a man having a heart attack.

"I was fine. I was completely normal," Hardman, 40, told ABCNews.com of how he felt in the days prior and on his way out to the call.

Once Hardman arrived on the scene, however, and began giving the patient emergency care, he felt an emergency within his own body.

"It felt like an explosion in my heart," Hardman said. "It wasn't painful but was just a sensation of an expanding feeling in my heart. It wasn't gripping and it didn't slow me down, but it was just there."

Hardman kept himself focused on his task at hand, not even telling his partner about his symptoms.

It wasn't until Hardman was in the back of the ambulance with the patient on the way to the Detroit Medical Center that his symptoms - nausea and weakness - became too much.

"I was worried I was going to pass out," he said. "I stuck my head in the window in the front of the truck and said, 'Hey, I think I'm going to have to be admitted. I'm having chest pains.'"

"That was it," Hardman said. "He [Hardman's EMS partner] said, 'Okay,' and checked on me a few minutes later."

Hardman's partner also called ahead to the hospital so that when their ambulance arrived doctors were waiting outside. One set of doctors took care of the patient, while another set took care of Hardman, the unexpected patient.

Hardman was admitted to the ER and underwent angioplasty to treat blockage in his left anterior descending coronary artery, otherwise known as the "widow maker" artery for its high mortality rate.

"You've got to have been in the right spot at the right time to survive one of those and I was one of those people," Hardman said. "I probably didn't have another 10 or 15 minutes for me just because I was going downhill so quickly. Had I not already been on the way to the hospital, I was done."

Hardman was released from the hospital yesterday, but not before getting a chance to meet the man whose life he saved, and who, inadvertently, may have saved his own.

"I walked over there and introduced myself again," Hardman said of the patient, who could not be identified or discussed further, other than to say that he is recovering well, due to federal privacy regulations.

Hardman said he feels "fantastic" and "perfectly normal" but knows it will be at least a few weeks to a few months before he returns to work full time.

In the meantime, Hardman said he is incredibly thankful to all the people who helped him, and he means everyone.

"The staff at the hospital that saved my life. My partner who, if it wasn't for him, I couldn't have driven myself to the hospital," he said. " I have to thank my wife. I have to thank my neighbors for mowing my yard while I was gone. I have to thank the city of Detroit for standing by my side. I have to thank everybody."