A firefighter remains in critical condition at Medical University of South Carolina in Charleston, after suffering a heart attack while working at an apartment fire over the weekend. Fire officials say they were told by hospital personnel that he showed slight improvement Monday.

A top fire official representing firefighters around the state said cardiac arrest among firefighters is a concern for fire departments across the country.

Murrells Inlet-Garden City firefighters were called to an apartment fire on Cambridge Circle around 3:30 Saturday. The fire started on a front porch and damaged one unit.

Officials say two firemen suffered from heat exhaustion while fighting the fire.

One has recovered, while the other was taken to MUSC from Georgetown hospital after suffering a heart attack.

His name and age have not been released.

Murrells Inlet-Garden City assistant fire chief Danny Lussier said the firefighter had been taking a rehab break, cooling down, drinking water and talking with other firefighters when he suddenly went into cardiac arrest.

Lussier said the firefighter was first taken to Waccamaw Community Hospital in Murrells Inlet, where his condition was stabilized. He was then transported to Georgetown Hospital, where he received a cardiac catheterization before being transported to MUSC, Lussier said.

Joe Palmer, executive director of the South Carolina Firefighters Association, said cardiovascular and stroke-related events are the leading causes of firefighter deaths nationally.

Palmer said physical fitness for firefighters is the top preventative measure. He said firefighters are tested annually by third party evaluators to determine their physical ability to do the job.

"Between those physicals, the department would offer some type of physical fitness training program. Anything from a weight room, exercise room to walking tracks, those type of opportunities that would allow firefighters to maintain their physical capabilities," Palmer said.

Offering firefighters rehabilitation on-scene at a fire event is also important, he said.

"For firefighters to able to take on additional fluids and have emergency medical services monitor their bodily temperatures, to ensure that it's safe for them to continue on working there."

Palmer said those fluids could be water, Gatorade or "any type of liquid nourishment."

Palmer, who is attending a state firefighters convention in Myrtle Beach this week, said the reality of firefighting is that it's usually done in a hot, humid and dangerous work environment.

"So again it goes back to just that preparatory of conditioning your body, conditioning your ability to be able to perform those functions, and your ability to rehabilitate yourself after an event."