An 18-month-old Prince William boy suffered a fractured skull after he fell from a second-story window in the Coverstone apartment complex Monday morning.

Prince William County police said the boy fell to the ground from an open window about 10:45 a.m. Monday. He was conscious when rescue authorities arrived and appeared to have a spinal injury. Police spokesman Dennis Mangan said that the toddler was released from the hospital yesterday morning and that his injuries were not life threatening.

Mangan said the boy's mother was checking something on the stove downstairs when she heard a youngster crying outside and recognized her son's cries. She then called 911.

Prince William Fire and Rescue officials arrived at the apartment, at 7640 Cass Pl., just after 10:50 a.m. and found the toddler in his mother's arms.

The boy, whose name was not released by authorities, was taken to Prince William Hospital and was flown later to Inova Fairfax Hospital.

Mangan said the police department responds to two or three such cases of children falling from open windows each year.

Prince William Fire and Rescue spokesman Steve Strawderman said that such incidents usually occur in the spring and early summer, when people begin to leave their windows open.

"Part of the problem we run into is that the kids' beds are located near the windows and they roll out of the window," Strawderman said. "Kids also lean up against screens and fall out.

"Screens are meant to keep bugs out, not to keep children in."