Official said Thursday morning they "made a lot of progress" using Portland cement mix to fight a massive industrial fire at an abandoned paper mill Thursday and that it is now "in check."
Morris Fire Chief Tracey Steffes said they have used 28 tons of Portland cement to smother the burning lithium batteries and there was no longer any active burning at the site. He said by Wednesday night, there were no more flames or smoke coming from the batteries.
Chief Steffes said that the unconventional method appears to be working, but warned it is possible the batteries could continue burning since they do not need oxygen to burn.
"When we smothered it with the concrete, we're not 100% sure that this thermal runaway is not continuing," Chief Steffes said. "It is probably continuing and hopefully it is going to consume what is left of the batteries underneath then it will be over. But there is a possiblility that as this continues that it does break through this Portland cement."
He said firefighters were digging a trench in the lowest corner of the building in case the fire breaks through the cement and water is needed
The evacuation order is in place due to the toxic fumes and smoke emanating from the building, stemming from as many as 200,000 lithium batteries exploding.
WATCH: Latest update from Morris officials
Firefighters believed thousands of pounds of lithium have burned out, allowing heavy machinery to tear off portions of the still burning building.
"They took that machine and stripped the front of that building of 150 feet of siding, which gave us our first look inside the building and what we were dealing with," Steffes said.
Before using cement, firefighters tried using a dry chemical to extinguish the fire.
"We brought over 1,000 pounds of Purple-K and we introduced that to the fire hoping we could kill it and choke it out," Steffes said. "The lithium fire laughed at the Purple-K. Didn't put a dent in it."
SEE MORE: Morris fire: Industrial blaze prompts evacuations of 1K nearby homes
Steffes said he has consulted with experts throughout the day on how to fight the fire without making it more of an environmental problem than it already is.
The blaze started just before 11:45 a.m. Tuesday at the old Federal Paper Board facility in the 900-block of East Benton Street.
"These batteries range in size of a cell phone to a little bigger than a car battery. As they get wet, they short out and they ignite and explode. That is the problem we are having," Steffes said. "The biggest hazard we have is the smoke and fumes as well as the gas from the fire. Highly poisonous and very deadly."
WATCH: Morris fire chief says crews working to smother blaze
Morris Mayor Chris Brown said the city was not aware of the batteries.
WATCH: Morris mayor says city unaware batteries being stored at warehouse now ablaze
"To our understanding, we were unaware of the batteries in the warehouse and only came upon it when the firemen started to do their work and push water onto the fire; they've been taking all the precautions necessary to make sure everything is safe and contained," he said.
The building's owner Jin Zheng said he was on the scene minutes after the fire started, but he was unable to get inside. He said the thick black smoke coming from the building was fueled by explosions of thousands of lithium batteries he had inside.
Zheng said he was storing supplies in the 70,000-square-foot warehouse because he was planning to open a solar power business by the end of the year.
"I have to say sorry," Zheng said.
Zheng said he has lost his life savings in the fire. He planned to get insurance after he opened the business. He also planned to have repairs done to the building's roof later this week, and he believes water dripping onto the batteries could have sparked the explosions and fire.
"It's not that lithium battery fires are new, it's just this quantity is something that hasn't been experienced, at least regionally here," Steffes said.
Tuesday's fire comes less than one month after the massive blaze at the Chemtool grease plant in Rockton. Special resources still in the area from that fire are now being utilized in Morris.
Officials evacuated the southeast side of Morris.
"We have determined that people will not return to their homes until the fire is much more controlled, if not completely out," said Michelle Pruin, with the Grundy County Health Department.
With ever-changing conditions, flames still roaring and toxic chemicals possibly seeping out into the air, families are out of their homes for at least another night.
"We don't have clothes, we don't have what we need here," evacuee Ana Luna said. "Pretty much we are just waiting to see."
Luna's family is sheltered where she works at a nearby Holiday Inn. She ran home and grabbed her kids Tuesday at a moment's notice.
"I have a lot of things at home that I need here but I didn't bring it because I didn't have enough time to pack everything," Fabian Luna added.
They're making the best of it, celebrating grandma's birthday huddled in a hotel room.
The Illinois EPA is monitoring air quality from several locations around town. At this point, they are planning no further evacuations. Steffes said Wednesday that air quality tests were "favorable."
The Grundy County Sheriff's Office said they are assisting with the response and the evacuations. The Grundy County Administration Building at 1320 Union St. is being used as a reception area.
Officials are asking that residents self-evacuate if they see or smell smoke and then report where that took place.
"It's a little scary, especially because we don't know what got in our house," evacuated resident Areli Soberano said.
Residents wanting to report smoke or smell or ask questions about shelter or the evacuation instructions may call 815-941-3408.
"We are going to be here for the long haul," Steffes said.
The Red Cross is supplying food and water to the more than 300 first responders battling the fire. Red Cross volunteers are also working to set up a reception center and shelter for those who have been evacuated at First Christian Church, 455 W. Southmor Road in Morris.
An update is expected from Morris officials at noon Thursday.