Anthony Lee, 16, and his brother, Diante Lamont Coakley, 21, have both been charged with first-degree murder, police told the Chicago Sun-Times Saturday night.
Eva Casara was 5 1/2-months pregnant when she was shot during an attempted drug deal ripoff on Wednesday, police said.
Lee and Coakley began shooting when the drug deal spiraled out of control, police said.
Police said Casara was not intentionally shot.
She was found in the snow on Wednesday night, and was bleeding from a gunshot wound to the head, the Chicago Tribune reported.
Casara was pronounced dead at 11 a.m. Thursday, but doctors were able to save her baby, who is now in critical condition.