Philly.com Staff A four-alarm fire that witnesses say began with an explosion tore through a Camden apartment complex, killing a toddler, and injuring five others. A four-month-old baby is among those hospitalized, and eight units were destroyed as a result of the blaze that began shortly before 2 a.m., according to Camden Fire Chief Michael Harper. "It's a bad fire," Harper said early this morning at the scene at the Gramercy Park apartments in the city's Fairview section. Harper said there was no known cause identified yet, and the fire that killed a 22-month-old was under investigation. Glenda Ransom, who lived in one of the burnt-out units, said she was awakened by a loud explosion. "It was a big boom," said Ransom, who has lived at the complex for 15 years. "Then I heard the girl screaming," Ransom said in reference to what she believed to be the mother of the child who was killed. "That baby was in there." Ransom said she did not personally know the woman who lived in the second-floor unit where the blaze started. "They were young, they were in their 20s," she said. "All I heard was her screaming," Ransom repeated, clearly shaken. Check back for more details.