MINNEAPOLIS (AP/CNN) – Authorities say, two brothers, ages 2 and 1, climbed over a barrier and accidentally fell 55 feet from the rooftop of a Minneapolis apartment onto a patio, killing one of them.

Minneapolis police received a call Thursday afternoon reporting the incident at a building along the Midtown Greenway. Police spokesman John Elder said workers in the area saw the children fall from an “upper story” and called 911. The workers provided immediate aid.

Elder said officers took over care of the children until they were relieved by paramedics and eventually transported to a hospital.

Minneapolis police say the other brother was injured in the Thursday fall and is expected to recover. A family friend told WWCO his injuries include three broken ribs, a fractured skull, broken arm, and jaw. The family friend also said the boys’ mother was nearby at the time and may have been in the bathroom when they fell.

Neighbors, witnesses and family members are cooperating with the investigation, Elder said.