Some Cobb County residents got an early-morning phone call Wednesday alerting them a 12-year-old boy was missing.

Hours after Marquise Jermaine Jackson was seen at East Cobb Middle School, the boy was still nowhere to be found, police said. Emergency responders feared the worst for Marquise, an insulin-dependent diabetic, Sgt. Dana Pierce with Cobb County police told the AJC.

“This child had some very recent medical issues," Pierce said. "If he did get in distress, would he ask for help?"

The missing child prompted emergency officials to activate the county's Code Red reverse 911 system, which has been in place since August 2009, Cobb County spokesman Robert Quigley told the AJC. The system is used about four or five times a year to alert residents to news, Quigley said. Early Wednesday, landlines within a six-mile radius of East Cobb Middle were called.

But the automated calls, placed between midnight and 1 a.m., shocked some residents, who in emails to the AJC said they weren't sure how to react to the call and questioned the timing. Some residents said they didn't realize the system existed until they were startled by the phone call.

The automated calls, with a robotic voice speaking, are computer-generated, and the calls are not made instantly, Pierce said. Calling all of the phones in a six-mile radius in a busy area is time-consuming, even for a computer system.

County leaders defended the decision to use the alert system, but acknowledged further discussion may be needed regarding when alert calls should be made. The system could potentially be very useful in a major event, such as a gas leak or flood.

"Why not just do the right thing?" Pierce said. "Err on the side of safety of that human being.”

Marquise was located around 2 a.m. in good condition, police said.