(CNN) A 9-year-old boy hit a car thief over the head with an iPad and his 16-year-old sister choked the thief and called 911 until he bailed out of the stolen SUV, police told CNN affiliate WGN.

The incident started outside a Domino's in the Chicago neighborhood of West Rogers Park on Sunday, police said.

The father of three children left the Toyota Highlander running as he went into the pizza shop and someone jumped in and drove off, according to police.

"I started shouting at him, 'Who are you? Get out of the car!' and he starts driving really fast down the road," the teenage sister, Imama Muratab, told WGN.

She said after she told the thief there was a baby -- her 4-year-old sister, Ayesha -- in the SUV, he told her to get out or he would shoot her.

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