20-year-old in custody for Brooklyn street festival shooting that killed 1, injured 11

Three months after gunfire shattered a neighborhood block party, killing one person and injuring 11 in the Brownsville section of Brooklyn, New York, police say they have a suspect in custody.

Brooklyn resident Kyle Williams, 20, has been charged with murder, attempted murder, criminal possession of a weapon and reckless endangerment in connection with the shooting, which took place during the neighborhood's annual Old Timers Day event at Brownsville Playground on July 27.

The crime was gang-motivated, NYPD Deputy Chief Michael Kemper said at a news conference Thursday afternoon.

Williams, accused of shooting and killing 38-year-old Jason Pagan, was taken into custody on Wednesday.

The "big break" came the first week of October when investigators released video of two women they were looking to identify, Kemper said.

"Tips started coming in and detectives ran with these tips and were successful in identifying both females," Kemper said, and that information led to Williams.

Two guns were used in the shooting, Kemper said.

Besides Williams, police have identified another person of interest, said Kemper. He said police are working with prosecutors "to establish probable cause on that second shooter."

"This was an important case to make," Police Commissioner James O'Neill said Thursday morning. "You think about what happened that night -- there's a crowd of hundreds of people [at a] 'family event.'"

"It was important that we all work together to make sure we were able to identify who the shooter was and bring them to justice," O'Neill said.

The incident left the neighborhood badly shaken. The shots may have been an exchange of gunfire between two or more suspects, authorities said.

"One of the worst experiences of my life," tweeted New York City council ember Alicka Samuel, who co-sponsored the event with council member Inez Barron and was there when the shooting took place. "How does such a beautiful and peaceful event become overshadowed by tragedy in seconds? We have to do more."

Pagan was struck by gunfire in the head and pronounced dead at a local hospital, according to the NYPD. Eleven other people -- six men and five women -- were shot and transported to the hospital for treatment, one in critical condition. The victims ranged in age from 25 to 55 years old, police said.

The shooting took place just before 11 p.m. as the crowd of about 2,000 was winding down the festivities.

The Old Timers event, which dates back to 1963, is a week-long festival that includes food booths, musical performances and a fashion and talent show.

Although regarded as one of Brooklyn's more dangerous neighborhoods, Brownsville has hosted the annual event for 55 years without incident.

Mayor Bill de Blasio, in a news conference on the day after the shooting, called the event "an example of everything good about Brownsville."

ABC News' Mark Crudele and Mark Osborne contributed to this report.