Two people were killed and six others — two of them children — were wounded in a shooting at a high school graduation party, police said Sunday.

Brent Matthew Banks, 37, was arrested after a four-hour standoff with police at a house in Mesa, east of Phoenix, Mesa Police Sgt. Ed Wessing said.

Preliminary information indicated that Banks was an invited guest at the party who got into a physical fight with his ex-wife late Saturday, Wessing said.

He allegedly went to his vehicle, got a gun, returned to the party and opened fire, killing his 38-year-old ex-wife and a 32-year-old man, Wessing said.

He said six others suffered minor injuries. They included a 10-year-old boy who was grazed on the head and an 8-year-old boy injured by bullet fragments.

Wessing said that when police arrived patrol cars were hit by gunfire and one officer was shot in the left arm. The officer's injuries weren't life-threatening and no other officers were hit.

Banks has not yet retained an attorney.