Arlington police said the 6-year-old boy was shot by his pre-teen brother.

A 6-year-old boy was shot in the head in Arlington Sunday and another child was shot in the buttocks in a separate shooting, according to police.

Arlington police said the 6-year-old boy was shot by his pre-teen brother.

The 6-year-old boy was taken to Mansfield Methodist, then immediately flown to Cook Children’s. The incident happened around 5 p.m. in the 1400 block of Cloyne Drive. Police said the boy is in "grave condition" Sunday night.

Previous reports from police indicated the child shot in the head was a toddler. On Sunday night, Arlington police said the weapon used in the shooting was a .22-caliber rifle.

In another incident in Arlington, police say an 8-year-old girl was shot in the buttocks, possibly while she or family/friends played with a gun. That incident happened at 12:26 p.m. in the 3800 block of Mahonia Way.

The girl was taken to Cook Children's and is expected to be OK, authorities said.

The gun used in the shooting of the 8-year-old girl was a stolen 9 mm Uzi from Bastrop County, Arlington police said Sunday night.

And also in Fort Worth Sunday morning, a 4-year-old child was shot and killed by a sibling, police said.

Follow WFAA's Lauren Zakalik for more information.