An 11-year-old boy was gunned down and his 16-year-old brother was critically wounded when someone knocked on the door of their western Pennsylvania home and began shooting when it was answered, authorities said Monday.

Police have not said whether they have identified a motive or a suspect in the shooting, which Allegheny County police Lt. Andrew Schurman said occurred at about 8:45 p.m. Sunday in Mount Oliver. The tiny borough is surrounded by Pittsburgh on all sides.

Other family members were home at the time but were not injured, Schurman said. He did not say who answered the door.

The 11-year-old, later identified by the county medical examiner as David McIntyre, was pronounced dead at the scene.

Pittsburgh Public Schools officials said the boy was a sixth-grader at the Pittsburgh Classical Academy, a magnet school for students in sixth through eighth grade. The wounded boy's name has not been released, but school officials said he's the dead boy's brother and attended Pittsburgh Carrick High School.

"Our thoughts are with the family at this time as they deal with this tragedy," the district said in a statement. Counselors were available to help students at the dead boy's school, which planned to send home a letter to help parents develop strategies "in coping with this loss."