5-year-old boy shoots 4-year-old boy in playground outside Washington, D.C.

A 5-year-old boy shot his 4-year-old neighbor in the back at a Maryland playground Thursday afternoon, authorities said.

The bullet passed through the young boy's upper torso while the two were playing in Hillcrest Heights, suburb about 10 miles southeast of Washington D.C., officials said.

Officers were called to the scene shortly after the shooting and found the victim, who was taken to hospital where he is expected to survive.

The young shooter was scared by what happened and ran away and hid the handgun in his family home, but it was later recovered, police said.

It is not clear where the gun came from, but authorities are questioning his parents and adults who have access to the apartment.

A man who described himself as the shooter's uncle told the Washington Post that witnesses believed the boy found the gun outside.

Dee Johnson, 29, said the child's mother lives in the apartment with her four children and does not keep guns.