Police found a 7-month-old boy — and no one else — when they arrived at the west Wichita home late Friday night.
Tipped by an anonymous call, police entered the duplex near 29th North and Tyler around 10:30 p.m.
The parents didn't arrive until just after midnight Saturday to their home in the 9000 block of West Meadow Park Court, police said.
The man and woman, both 31, were booked into the Sedgwick County Jail on suspicion of aggravated endangering a child.
Wichita police Sgt. Steve Yarberry said the baby was under protective custody Saturday.
Police saw the baby was awake in his crib when they entered the home, Yarberry said.
A neighbor, however, said the parents appeared to have been gone most of the evening.
"I'd been sitting out in my front yard since about 7 o'clock," said the neighbor, who asked not to be identified.
The neighbor said a police car drove up to the duplex at about 7 p.m., knocked on the door, then left when nobody answered the door. Soon afterward, the neighbor saw the parents arrive on their motorcycles, then quickly leave.
"I bet they weren't there five minutes," she said.
Yarberry said police get calls to check on the welfare of children left home alone, but not that young.
"This was an unusual case; 7 months is way too young," Yarberry said.
Kansas does not have laws about when a child is old enough to stay at home alone or baby-sit others, according to Safe Kids Kansas, a nonprofit child safety organization in Topeka.
But Safe Kids recommends children not be left alone until about age 12, depending on the maturity of the child.
"If they're under 16 years old, we take it very seriously," Yarberry said.
More than 2,000 school-age children die from unintentional household injuries each year, Safe Kids reports, including fire, suffocation, drowning, choking, firearms and poisoning.
The neighbor of the couple arrested in west Wichita said she heard a knock at the door about 12:30 a.m. Police said the parents claimed she was supposed to be watching the boy. She said she was shocked.
"I've never baby-sat that baby," the neighbor said.
Yarberry said the couple were taken to City Hall for questioning, then arrested.