With no explanation, label each line with "location-GPE", "O", "event-attack/battle/war/militaryconflict", "product-airplane", "art-broadcastprogram", "art-film", "art-music", "art-other", "art-painting" or "art-writtenart" preceded by ":".
His
son
,
Stephen
,
was
a
casualty
of
the
9/11
attacks
when
American
Airlines
Flight
11
crashed
into
the
North
Tower
.
His:O
son:O
,:O
Stephen:location-GPE
,:O
was:O
a:O
casualty:O
of:O
the:event-attack/battle/war/militaryconflict
9/11:event-attack/battle/war/militaryconflict
attacks:event-attack/battle/war/militaryconflict
when:O
American:product-airplane
Airlines:product-airplane
Flight:product-airplane
11:product-airplane
crashed:O
into:O
the:O
North:location-GPE
Tower:location-GPE
.:O