Overnight rain helped to suppress an uncontrolled fire at a North Carolina fertilizer plant, but fire officials warned Thursday that it has also pushed smoke closer to the ground, creating a health hazard.

There is still a risk of an explosion and officials still want people to stay away, Winston-Salem Battalion Chief Patrick Grubbs said during a briefing. The fire has gotten a bit smaller, but there is still an active fire, he said.

“Our message has stayed the same the whole time — we’re asking all the citizens to stay out of the area and if they’re in the area to evacuate,” Grubbs said. Anyone with respiratory issues should stay out of the smoke cloud, he said, but the smoke also isn’t good for anyone who is healthy.

The area where officials have called on people to evacuate includes about 6,500 people in 2,500 homes, officials have said. There’s no projected return time for that area, Grubbs said.

The fire began Monday night at the Winston Weaver Company fertilizer plant on the north side of the 250,000-person city and quickly consumed the entire building, which collapsed. Firefighters battled the blaze for about 90 minutes, but the risk of explosion forced them to retreat. No injuries were reported. An estimated 500 tons (454 metric tons) of combustible ammonium nitrate were housed at the plant and nearly another 100 tons (91 metric tons) of the fertilizer ingredient were in an adjacent rail car.

Thursday’s rain also means that drones and helicopters can’t survey the fire from above, Grubbs said. Fire personnel are monitoring the blaze and watching for any changes in conditions, but they are staying about 300 feet (91 meters) away, he said. A fire truck at the scene is putting water on hot spots.

There are specialists from several states involved and air monitoring equipment around the scene is checking for different gases, Grubb said.

A 12-person team, including federal and state investigators, is collecting information, conducting interviews and reviewing drone footage to help understand the damage that has occurred, Fire Investigator Rick McIntyre said. An on-scene investigation will only happen once it is safe, he said.

Officials initially thought the situation could end in 36 hours, maybe even two days. But Winston-Salem Fire Chief Trey Mayo said Wednesday that there were too many unknowns to make any predictions.

(AP)