(CNN) -- An explosion at a Hawaii storage facility that housed fireworks left four people dead Friday, the Honolulu Police Department said.
The incident occurred around 9 a.m. (3 p.m. ET) Friday at a Waikele facility, police said in a statement.
The storage unit was being used by a licensed explosives company that was contracted to stabilize and destroy fireworks that had been seized as evidence, police said.
"This incident is a tragic reminder of how dangerous fireworks can be, even when handled by experts," police said.
Fire and police personnel, along with agents of the U.S. Bureau of Alcohol, Tobacco, Firearms and Explosives, were on the scene in an industrial section outside of the city, said Louise McCoy, a spokeswoman for the mayor's office.
A fire was still burning hours later, she said.
Three men in their 20s and a man in his 50s died, police said. Two other men in their 20s were injured, one critically.
Two bodies had been recovered, police said, adding the fire must burn out before they can enter the unit to recover the others.
CNN's Greg Morrison contributed to this report.