(CNN)A fire at a waste management facility in South Florida has continued burning for nearly a week, prompting officials in Miami-Dade County on Friday to close parks, dismiss two schools and urge residents near the waste-to-energy plant to stay indoors due to air quality concerns.
The fire that started Sunday at the Covanta Energy plant in Doral has has been burning in two structures at the facility, Miami-Dade Mayor Daniella Levine Cava said during a news briefing Friday. The mayor said officials are monitoring the fire to determine if the smoke from the blaze is toxic.
The cause of the fire is still under investigation. No injuries have been reported.
The facility, operated by waste management company Covanta, diverts "waste from landfills to generate energy from the combustion of municipal solid waste," its website says.
Miami-Dade County officials warned residents in a Friday update they "anticipate an increase in smoky conditions" as firefighters reach the center of the fire.
The county said the Environmental Protection Agency (EPA) urged residents who live near the site to stay indoors on Friday, adding that young children, pregnant mothers, older adults and anyone with preexisting respiratory and cardiac conditions should take extra precautions, such as wearing a mask outdoors.
"Please keep your windows rolled up if you need to drive through the area, and run your air conditioning at home to re-circulate air in your house," the county update said.
The county said in its update that the Doral Glades Park and the Doral Legacy Park were closing on Friday, and all outdoor activities scheduled in the city would be rescheduled.
Miami-Dade County Public Schools said in a written statement that children at two schools in the district would be dismissed early due to air quality concerns.
Parents and guardians of students attending the Andrea Castillo Preparatory Academy and Ronald W. Reagan Doral Senior High School were encouraged to pick up their children early from school, the school district said in a statement.
Firefighters with Miami-Dade Fire Rescue are "working tirelessly to put out the blaze," the county said, including the demolition of one building that will allow firefighters to better fight the blaze.
Why is the fire still burning at the waste plant?
During a news conference Thursday, Miami-Dade Fire Rescue Chief Ray Jadallah explained the exhaustive efforts by fire crews to contain the blaze and why it's continued burning for days.
Jadallah said about 100 firefighters were working the fire and explained there were four separate ongoing operations attempting to battle it, including efforts to extinguish the trash currently on fire and the two buildings ablaze; a partial demolition of a building on the southeast side of the property to gain better access; shuttling trash near the fire to another area to prevent the blaze from worsening; and an investigation to determine the cause of the fire.
"I know this question comes up quite often is how long is the fire going to burn?" Jadallah said. "Until we actually remove the remainder of the walls, and actually get the apparatuses in there, the heavy machinery to remove the trash, we won't have an exact idea."
Fire operations were temporarily put on hold around 5 a.m. Friday so crews could demolish a wall to allow them more access to the area. Jadallah said crews moved in large machinery to remove parts of the wall but were met with worsening smoke due to a mixture of the overcast weather, the machine interacting with burning trash and the temporary halting of firefighters working to douse the blaze.
Around 1 p.m., fire crews resumed dousing the blaze with multiple firetrucks.
"We continue to partner with our numerous state and federal agencies, including the EPA and ATF," Jadallah said.
"I know that we faced some significant challenges, as we've already discussed, over the course of the last several days, including today, but we continue to move swiftly and we're making some significant progress," he said.