With no explanation, label each line with "O", "organization-other", "organization-government/governmentagency", "person-soldier", "event-attack/battle/war/militaryconflict", "art-broadcastprogram", "art-film", "art-music", "art-other" or "art-painting" preceded by ":".
Some
researchers
theorize
that
Mexican
Rurales
led
by
Captain
Alfredo
Carrillo
,
who
had
survived
the
Skeleton
Canyon
Massacre
in
1879
,
led
the
ambush
of
the
Cowboys
.
Some:O
researchers:O
theorize:O
that:O
Mexican:organization-government/governmentagency
Rurales:organization-government/governmentagency
led:O
by:O
Captain:O
Alfredo:person-soldier
Carrillo:person-soldier
,:O
who:O
had:O
survived:O
the:O
Skeleton:event-attack/battle/war/militaryconflict
Canyon:event-attack/battle/war/militaryconflict
Massacre:event-attack/battle/war/militaryconflict
in:O
1879:O
,:O
led:O
the:O
ambush:O
of:O
the:O
Cowboys:organization-other
.:O