. >> reporter: this corner of northern uganda, where the river nile cuts through lush rain forest and savannah, is known as the pearl of africa. a nickname proudly reclaimed by mercy falls national park even after decades embroiled in environmental crisis. it's been a long seven-hour car ride across two continents. it is not an easy place to get to. but on the horizon, a creeping new challenge. one that again threatens the park and its wildlife. clouding its future in uncertainty. >> are you excited to be here? >> very excited. >> reporter: we've traveled here with shabani. >> i'm resting up to be excited. >> we're seeing the nile. it's amazing to see the nile. >> reporter: she's a wild-expert and national geographic explorer born and raised in neighboring kenya. >> yeah, there they are, coming out of the water. >> rrr! we're speaking hippo. >> reporter: she's helping explore how this delicate ecosystem is returning from the brink. >> you're jumping out of your skin to get out. >> reporter: despite the wait she isn't disappointed. a special sighting right away. >> these are endangered

uganda bombings, but before westgate. 2012 is when they pledged allegiance to ayman al zawahiri. today, al shabaab carried out their deadliest attack yet in kenya, at the only public university in northernis school has been open only for about four years. it has about 900 students. today, just before dawn at about 5:30 a.m. local time, masked al hab bab shabaab gunman shot their way through the gates of the school and forced their way in and then they they just started killing people and taking hostages in the university dormitories. all the students had basically been asleep when the shooting started. one eyewitness told reporters that the gunmen at his door opened doors and screamed are you christian or muslim. he said, quote, if you were a christian, you were shot on the spot. it took two hours for security forces to arrive at that campus. and begin evacuating the students from the dorms. finally, it was after dusk. it was about 15 hours later when officials finally announced that the operation was over that they had killed four terrorists and the siege was done. 587 people were safely evacuated from that campus today, but at least 147 people, mostly students were killed. 147 people.