CAIRO - A Nile River passenger boat sank on Thursday killing at least six Christian school girls who had been on a church outing, Egypt's official Middle East News Agency (MENA) and security sources said. "The boat was on a Nile trip organised by a church in Maadi (in Helwan governorate South Cairo) and had 19 females on board which was more than the boat could handle," MENA said citing a senior official at the site of the accident. Ten girls have been rescued, security sources said. The outing was for girls aged between 10 and 18 years old. Public river boats in Egypt are often overcrowded and passenger manifests are often absent or inaccurate, but the boat which sank was not a large vessel.