A man who said he didn’t think his gun was loaded when he opened fire at Brooklyn’s J’Ouvert street party has been arrested for the shooting of a 22-year-old college student celebrating the festival, police said.

Reginald Moise, 20, is accused of fatally shooting the St. John’s University student, Tiarah Poyau, in the face on Monday, police said.

According to Chief of Detectives Robert Boyce, Moise hid the gun at a friend’s home and admitted to shooting a gun — but said he thought it was not loaded. Moise is charged with second-degree murder, with depraved indifference.

Brooklyn’s J’Ouvert festival — the Caribbean nocturnal street party beset by persistent, annual violence — will go on next year, despite a bloody Monday that left four shot, two fatally, Mayor Bill de Blasio said on Tuesday.

A day earlier, de Blasio said “all options are on the table” when asked if he might cancel the event. But on Tuesday, he said, “I think it was very clear yesterday that we were not including the option of ending something which has gone on for decades and decades.”

Over the past 20 years, the NYPD handled 21 shootings or homicides at J’Ouvert, which now attracts an estimated 250,000 to central Brooklyn to celebrate Caribbean culture in elaborate costumes.

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“We have to find out a way to make it safer,” said de Blasio, who last week promised “the safest J’Ouvert ever”: hundreds of floodlights, arrests of parolees and gang members and about 3,400 cops — double the number patrolling the 2015 party.

Police are still looking for whoever shot Tyreke Borel, 17, of Brooklyn. His companions left him after the shooting, and he was found dying on a bench. Medics who found him didn’t realize he had been shot, suspecting instead he was merely intoxicated or suffering from a drug overdose.

The stepped-up policing came after the 2015 J’Ouvert, in which Carey W. Gabay, a lawyer in the administration of Gov. Andrew M. Cuomo, was slain by a stray bullet fired in a gang battle.

On Tuesday, de Blasio said he hoped to tame J’Ouvert as city officials had done with misbehavior at the St. Patrick’s and Puerto Rican parades. Both events were far more rowdy in years past than their current incarnation. When a reporter noted that most of the St. Patrick’s and Puerto Rico parade mayhem centered on intoxication and disorderly conduct, not shootings, de Blasio said: “I have a different view of it. Let’s have some of the experts speak first.”

But William Bratton, de Blasio’s NYPD commissioner, told the reporter: “You’re correct. The nature of some of the violence that’s associated with J’Ouvert is different than the levels of violence at other events.”