(CNN) Three men have been arrested in two separate shootings in Philadelphia last weekend that left a 2-year-old girl dead and an 11-month-old child critically wounded, police said.

Freddie Perez and Tayvon Thomas were arrested in the death of Nikolette Rivera, Philadelphia police said. The toddler was killed Sunday when someone fired a 7.62 mm rifle into a home in Kensington, in northern Philadelphia, hitting her in the back of the head. She died at the scene.

Francisco Ortiz was arrested Thursday in the shooting of the 11-month-old child, who remains in "very, very bad condition," said Philadelphia police Capt. Nicholas Brown.

The baby was shot four times while sitting in a vehicle Saturday in the city's Hunting Park area around 8 p.m., Brown said. The baby was hit once in the head, once in the neck and twice in the buttocks with rounds from a 9 mm gun, he said.

Police arrested Perez Tuesday in Chester, Pennsylvania, and Thomas was arrested Thursday in Philadelphia. Both were charged with murder, nine counts of attempted murder, criminal conspiracy and related offenses, police said.

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