Two people are in police custody after a shooting left a rookie police officer and a bystander dead during a dance at the Gila River Indian Reservation in Arizona, early Saturday, authorities said.

The FBI is investigating how Officer Joshua Briese, who was still undergoing field training, was shot and killed. The bureau confirmed Sunday that two suspects — one adult and one juvenile who were not identified — were both in custody and both receiving medical care.

Another police officer was shot and in “serious but stable” condition, police said. Four others were also shot at the dance, police said, one of whom has died. The rest are being treated at local hospitals but their condition is not known.

“Our hearts and prayers are with these police officers, their families, and everyone impacted by this tragic incident,” the FBI said in a statement.

The Gila River Indian River Community Council said on its Facebook page that it held a meeting Saturday to call a moratorium on dances.

NBC affiliate KPNX of Phoenix spoke to someone who was at the dance. “It was scary. I was scared when I heard the gunshots, we all dropped to the ground,” said the person who asked not to be named.

Police forces, lawmakers and community groups all paid tribute to Briese. “Our hearts and prayers are with these police officers, their families, and everyone impacted by this tragic incident,” Gila River police said on Facebook.

Stephen Roe Lewis, governor of the Gila River Indian Community, said in a press release: “I know I speak for our entire Community when I say that we grieve for our fallen and injured police officers and every Community member touched by such tragic violence. Nothing cuts deeper than a life cut short.”

Briese’s father was Dave Briese, a sheriff’s deputy who died in a car crash in 2006, said a post on the Yellowstone County Sheriff’s Office Facebook page.

“Knowing Dave & Josh are together again, both left this world serving their community and doing what they loved,” the post read.

The Arizona Trooper’s Fraternal Order of Police Lodge 32, said on X that the other officer who was shot was Briese’s field training officer.

This article was originally published on NBCNews.com