Updated

A 1-month-old baby found on the side of an Oklahoma interstate in a car seat stuffed with $5,500 in cash and a birth certificate was in state custody Monday as authorities continued to investigate why the boy was abandoned.

Oklahoma City police said a church group returning from an amusement park spotted the child Saturday about 10 feet (3 meters) from the shoulder of Interstate 40. Sgt. Gary Knight said Monday that officers also found a Social Security card with the baby.

Police said they located the child's mother through family members and that she's been taken to a hospital to be evaluated.

"We don't know why she did what she did ... but people do the strangest things sometimes," Knight said. "I don't recall seeing a case like this where a baby was just left on the shoulder of a highway. This could have had a very tragic ending."

Emergency workers estimated the child had been left in the 91-degree heat about 30 minutes, but said he appeared to be well cared for before being left on the interstate.

Ken Angel, pastor of Abba's House of Worship Center in Ada, Oklahoma, whose group spotted the child, credited divine intervention in finding the child.

"I feel like God used our youth group to save someone's life Saturday because we're here on Earth to fulfill a redemptive purpose," Angel said. "God stepped in."

He said about 15 members of the 120-congregant church were traveling back to Ada, about 84 miles (135 kilometers) southeast of Oklahoma City, when the youth leader saw the car seat. The group had been at an amusement park in Oklahoma City.

Sheree Powell, a spokeswoman for the Oklahoma Department of Human Services, said she couldn't release any information about the child.