JACKSONVILLE , Florida ( CNN ) -- Four people were killed and several injured after an explosion Wednesday at a chemical plant sent a thick plume of smoke over a section of Jacksonville , authorities said . A thick plume of smoke rises Wednesday at a chemical plant in Jacksonville , Florida . `` Literally , it 's a hellish inferno . There is no other way to describe it , '' said Fire Department spokesman Tom Francis . Fourteen people were hospitalized after the blast at the T2 Lab on Faye Road , in an industrial area on the waterfront in north Jacksonville , Francis said . Officials initially ordered an evacuation of nearby businesses , but by 4 p.m. the order had been lifted after tests of the air found no toxicity , Francis said . Firefighters were still battling hot spots , and the effort will be going on for `` quite some time , '' he said . See an I-Report account about the blast » . Six of those injured were transported to Shands Hospital in Jacksonville , hospital spokeswoman Kelly Brockmeier said . A Shands official said the hospital incident command system had been activated -- something done to put the staff in high alert in anticipation of trauma patients . A woman who answered the T2 Lab 's 24-hour facility emergency phone said the plant manufactures ecotane , a gasoline additive that reduces tailpipe emissions , according to the laboratory 's Web site . See a map of the site of the explosion » . The billowing black smoke could be seen from the city 's downtown , said Florida Times-Union reporter Bridget Murphy . Murphy said she talked to several workers as they walked out of the area , and they were `` shaken to the core . '' `` They described a hissing noise and then a sound wave , '' she said . Antonio Padrigan was trying to get in touch with his son , who works in a plant in the area , but was having no luck reaching him on his cell phone . `` He was shook up when he called me , but I ca n't get through to him anymore , '' Padrigan said . `` I do n't know if he 's in the hospital or what . '' CNN I-Reporters Jonathan Payne and his son Calvin , 16 , shot pictures of the explosion . They felt the blast shake their home , about 15 minutes away , and went to see what was going on . Carlton Higginbotham , 63 , was working at home on Townsend Boulevard in Jacksonville when a loud boom shook his house , he said . `` It was a gunshot-type explosion ; it was n't a rumble , '' he said . Higginbotham , an insurance salesman , and his neighbor ran outside and noticed thick smoke billowing from the other side of the St. Johns River , which separates his neighborhood from the site of the blast . `` The cloud that came out of it was white , some would say mushroom-shaped , '' Higginbotham said . `` It was followed by dark , dark smoke . '' E-mail to a friend .
NEW : Fire Department spokesman : 14 have been taken to area hospitals . Firefighters still fighting hot spots Wednesday afternoon , official says . `` It 's a hellish inferno , '' he tells reporters .