OAKLAND — A man and a 13-year-old boy have been charged in an improvised explosive device detonation July 23 that injured numerous Oakland police officers at a downtown march, authorities said Thursday.

Both suspects have admitted their involvement and the boy has apologized to police, authorities said.

The man charged was identified as Giovanni Gaines, 23. He has been charged with four felony counts of exploding a bomb causing great bodily injury, exploding a bomb with intent to injure, possession of a destructive device near populated locations and possession of a destructive device.

He is being held in lieu of $3,000,050 bail and is due in court Nov. 15. He also faces possible federal indictment.

According to authorities, the boy has pleaded guilty to felony criminal conspiracy.

The attack on the officers happened after a vigil July 23 seeking to honor 18-year-old Nia Wilson, fatally stabbed a day earlier on the MacArthur BART station platform. Several hundred people marched south from the station along Telegraph Avenue to the city’s Uptown neighborhood with police following to protect them.

But when police formed a skirmish line to handle fights among some in the crowd, someone threw an explosive device described as an altered illegal M-1000 firework that was wrapped in a copper-like material to contain shrapnel attached to the device. Four officers suffered burns and puncture wounds while others sustained momentary blindness, deafness and disorientation, authorities said.

The resultant investigation, led by Lt. James Beere, one of the injured officers, determined Gaines handed the device from a backpack to the 13-year-old, who threw it before they both fled the scene on mountain bicycles. Authorities said the two were friends.

Police and the Federal Bureau of Investigations viewed and analyzed more than 100 pieces of video surveillance, including some from local television station KGO-TV, of the scene.

Police and the FBI were able to first identify the 13-year-old who was arrested Sept. 28 and cooperated with investigators, authorities said. Gaines was subsequently identified as the main suspect. After more investigation and surveillance, he was arrested Nov. 1 at his home on Empire Road in East Oakland.

Beere, who suffered a burn and puncture wounds to his leg, said Thursday he was grateful no one was hurt more seriously and that the individuals responsible “have been brought to justice.”

Staff writer Harry Harris contributed to this report.

#EXCLUSIVE: #Oakland police have arrested a bombing suspect who is charged with targeting officers during a huge march in July to protest the fatal stabbing of Nia Wilson at a #BART station. https://t.co/LMAbRkNn6o — ABC7 News (@abc7newsbayarea) November 8, 2018

Contact George Kelly at 408-859-5180.