A Texas fertilizer plant explosion that occurred in a small Texas town Wednesday night killed an estimated of five to 15 people, officials in the investigation said. Some of those killed in the explosion where firefighters who had been battling the blaze at the factory that caused the explosion.

Images of the gigantic fireball that devastated the tiny town of West, TX, 20 miles north of Waco, were petrifying, and at a very sensitive time. The event occurred just two days after a bombing killed three people and injured many others at the finish line of the Boston Marathon Monday. Officials said that there was no immediate indication that the fire was anything other than an industrial accident, however, they added that are examining all possibilities.

“There are homes leveled. There are businesses leveled,” Waco Police Sgt. Patrick Swanton said during a new briefing early Thursday. “There is a massive devastation in the downtown West business area.”

He said that the death toll is preliminary, adding that rescue crews have yet to enter the most damaged areas of the West Fertilizer plant and the surrounding town.

At least three to five firefighters who were in the area of the blast were unaccounted for, but one of them was located at an area hospital, according to Swanton. The first responders were urgently trying to evacuate residents after realizing that the fire, which began at 7:29 p.m. Wednesday, could potentially cause a huge explosion. The first report of the explosion came at 7:53 p.m.

According to West Mayor Tommy Muska, 50-60 homes within a five-block radius of the factor were heavily damaged. The West Rest Haven Nursing Home was evacuated at the time of the blast because of its proximity to the fire; its residents have all been brought to a safe location, said the mayor.

The whole neighborhood around the plant has also been evacuated, because rescue workers were searching house to house, looking for people who may have been injured, killed or trapped in the pile of debris. Dozens of people taken to area hospital for treatment had injuries ranging from minor to critical.

Officials said that it was too early to say how the fire that caused the explosion began. The federal bureau of Alchohol, Tobacco, Firearms and Explosives and the U.S. Chemical Safety Board, all said that they are sending investigators to West, TX to assist local authorities in their investigation.