A massive gas line explosion rocked a neighborhood of northwest Baltimore on Monday morning, killing at least one person and injuring four, officials said.
The blast — near Labyrinth and Reisterstown Roads — happened a little before 10 a.m. ET and killed at least one woman, according to the Baltimore City Fire Department.
Three victims were quickly found and rushed to the hospital, city fire spokeswoman Blair Adams told reporters at about noon, moments after firefighters had just pulled a fourth injured resident out of the rubble.
Firefighters believed they were close to finding a fifth injured resident, according to Adams.
"Right now it’s unclear what caused the explosion. We are continuing to search for any additional occupants," Adams said.
"It’s a labor intensive rescue. Again, it was a major gas explosion so you had homes that were pretty much crumbled — a ton of debris on the ground that we're trying to comb through."
Three homes appeared to be wiped out in the explosion, as firefighters frantically sifted through rubble to look for more possible victims.
"We are on the scene and working closely with the fire department to make the situation safe," Baltimore Gas and Electric Company spokeswoman Tasha Jamerson said in a statement.
"Crews are working to turn off gas to the buildings in the immediate area. Once the gas is off we can begin to safely assess the situation including inspections of BGE equipment."
Firefighters were in full gear as they battled the debris and 90-degree heat with high midday humidity that made it feel like 100 degrees.
"It's a lot of work by hand, a lot of back-breaking work," International Association of Fire Fighters Local 734 President Rich Langford told NBC News. "It's extremely hot and our guys are pushing through to get the job done."
This is a developing story, please refresh here for updates.
This article was originally published on NBCNews.com.