At least 16 people were injured by a massive explosion Wednesday night following the Los Angeles Police Department’s attempts to detonate a cache of illegal fireworks in South Los Angeles, the Los Angeles Fire Department said.

Nine of the injured are LAPD officers, one is an ATF officer and six are civilians.

Three of the six civilians are being transported to the hospital with serious injuries. The others, along with the LAPD officers and the ATF officer, are being treated for minor injuries.

“Our Bomb Squad officers were in the process of seizing over 5,000 pounds of illegal fireworks in the area of 27th Street and San Pedro. Some of the fireworks were being stored in our Bomb Squad trailer as a precautionary measure,” the LAPD wrote on Twitter.

The explosion damaged cars and surrounding buildings and left debris scattered on the streets.

The LAFD said several homes impacted and LA Building and Safety is evaluating them to determine their status and see if anyone will be displaced.

Police said evacuations will be going on “for hours.”

They added that it’s unknown at this time what caused the explosion.

PIOs were at the scene late Wednesday and the investigation is ongoing.

ABC News’ Marilyn Heck contributed to this report.