NEW : Officials claim air force shot down rebel planes . The organization 's 45-page study said 2,000 civilians have been killed and another 5,000 have been wounded . Up to 250,000 dead , 50 wounded in capital , Human Rights Watch . Both sides to blame for rise in civilian casualties , Colombo says . 50 civilians trapped in Katunayaka conflict zone , aid groups say .
NEW : Officials claim air force shot down rebel planes . Up to 250,000 dead , 50 wounded in capital , Human Rights Watch . Both sides to blame for rise in civilian casualties , Colombo says . 50 civilians trapped in Katunayaka conflict zone , aid groups say .