OAKLAND (CBS SF) — A 13-year-old and 23-year-old man have been arrested for igniting ‘an improvised explosive device’ that injured 10 Oakland police officers during a demonstration in July, authorities announced Thursday.

The attack took place on July 23rd, during a gathering at the MacArthur BART Station to protest the stabbing death of 18-year-old Nia Wilson. Authorities said at least two M80- or M1000-type devices were thrown at officers, injuring them.

At the beginning of the investigation there were few leads. Members of the intelligence section, felony assault and patrol were able to recover and analyze over 100 pieces of video surveillance footage.

Eventually, investigators were able to identify a person of interest and he was located.

Detectives prepared a search warrant for the subject’s residence and a Ramey warrant was signed for his arrest. The 13-year-old was taken custody and evidence linking him to the crime was recovered during the search.

“He made a full confession, apologized for injuring the officers and cooperated with the investigation,” Oakland police said in a news release. “He provided a formal apology to the Oakland Police Department and plead guilty for felony criminal conspiracy.”

Several search warrants were prepared and authorized for social media profiles, emails accounts, cell phone data and location information on a second suspect — identified as 23-year-old Giovonni Gaines.

Through the assistance of the Federal Bureau of Investigation and the Oakland Police Department’s Intelligence Section, Gaines was tracked down and arrested on Nov. 1.

“This adult suspect provided a full confession, admitted to possessing the explosive device, providing it to the minor co-defendant and then igniting the device,” police said in release.

Gaines faces several charges — assault with a deadly weapon on a police officer likely to cause great bodily injury, two counts of possession of an explosive device, igniting a destructive device with the intent to injure and four counts of maliciously exploding a device with the intent to cause great bodily injury.

He was being held on $3 million bond in Santa Rita Jail and scheduled for a bail hearing on November 15 at 9 a.m. at the Rene C. Davidson Alameda County Courthouse.