A 10-year-old girl drowned in Fairfax County and a 19-month-old boy was hospitalized in Prince George's County as a result of separate water-related accidents yesterday.

In Fairfax County, a girl drowned after slipping into a deep section of a stream that feeds Lake Barcroft near Annandale, police and witnesses said. The girl, identified as Bouloy Khambay of 3459 Lake St. in the Culmore area, was pulled from the water about 15 minutes after going under. A Fairfax County firefighter used snorkeling equipment supplied by a neighbor to dive into the stream. The girl was pronounced dead at Fairfax Hospital.

Neighbor Michael Rose said that shortly before 11 a.m. yesterday, six children were playing in the stream bed near an incline where the creek cascades in a waterfall into Lake Barcroft. Three children fell into the water and two were rescued by an older girl. The older girl lost her grip on the victim, who was pulled into the stream by rapidly moving water.

Shortly before 11 a.m., Mount Rainier volunteer fire and rescue workers responded to the report of an apparent drowning of a 19-month-old boy. The boy apparently had wandered from a house in the 4200 block of 34th Street and fell into a neighbor's pool. A relative pulled him from the pool. He was flown to Children's Hospital, where he was listed in critical condition.