Four firefighters were injured in separate fires within hours of each other over the Fourth of July holiday.

One firefighter remains hospitalized in serious condition after suffering from over-exertion and another firefighter at the same fire suffered first and second-degree burns. The fire occurred on the 3600 block of Pennsylvania.

In north St. Louis, one firefighter suffered heat exhaustion on the 5100 block of Cates.

In south St. Louis, on the 3100 block of Oregon one firefighter suffered first- and second-degree burns.