A 3-year-old girl fell out of fourth-floor window in Montgomery County on Monday morning and was taken to Holy Cross Hospital in serious condition, officials said.

Police are looking into the possibility that the child was inside a room with her 5-year-old-brother and one of them opened the window to look at the snow.

The incident happened shortly after 9 a.m. in the 3800 block of Bel Pre Road, which is about four miles north of downtown Wheaton. Two adults were in the apartment at the time of the fall, but apparently were not in the room with the open window. The investigation into the incident is ongoing, said Capt. Paul Starks, a police spokesman.