"We escaped a real tragedy on this one," said Deputy Commissioner James Kelly with the Philadelphia Police Department. "We would have lost the entire block at a minimum."
Police say neighbors called 911 after seeing smoke coming from the home on Montague Street Friday night.
After firefighters went inside and discovered the explosives, they called police, investigators say. Counter-terrorism officers and the Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF) were called to the scene as well.
According to investigators, 27-year-old Evgenii Sadrislamov was manufacturing explosives in the basement inside of a makeshift lab.
They reportedly discovered 50 pounds of highly volatile explosives in the home.
"He clearly knew that he was engaging in dangerous, illegal activity," said Eri DeGree with the ATF. "The fact that a fire led to his lab's discovery, rather than a blast that leveled the building, was fortunate."
Sadrislamov was on probation after pleading guilty to similar charges in 2020 for having explosives.
Investigators are unsure why he created the explosives and are still investigating.
Sadrislamov is charged with arson, weapons of mass destruction, causing catastrophe, possession of an instrument of crime, and related offenses.
Sadrislamov remains in custody on approximately $1 million bail as the investigation continues.
His preliminary hearing is currently scheduled for October 22.