Updated 02/13/14 – 1:52 p.m.

ROMEOVILLE, Ill. (CBS) — Romeoville police were questioning four “people of interest” about the shooting of a woman and her teenage daughter Thursday morning.

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Romeoville Police Chief Mark Turvey said investigators haven’t yet determined a motive for the shooting of a 33-year-old woman and her 15-year-old daughter as they were getting ready to go to school.

The two were shot around 7 a.m. as they were getting into an SUV in their driveway in the 300 block of Emery Avenue.

“A male subject approached the car and shot the daughter, and then shot the mother,” the chief said. He said the gunman specifically targeted the women.

Turvey said the four people being questioned range in age from their late teens to their early 20s.

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“We don’t know that any of these four are the offender, but we’re confident that the offender … either he’s no longer a threat, or he’s no longer in the area,” he said.

He also said shootings are very rare in Romeoville.

“If we get one a year, that’s a lot,” Turvey said.

The chief said the girl who was shot was airlifted to Loyola University Medical Center in Maywood. Her mother was taken to Adventist Bolingbrook Hospital.

Romeoville schools were placed on a “soft lockdown” while police conducted a search immediately after the shooting. While the schools initially told parents to send their kids to school, they were later told to keep them home until the lockdown was lifted.

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Those kids who did go to school while buildings were locked down were sent to the Romeoville Recreation Center until the lockdown was lifted around 9:30 a.m.