A、On Christmas Eve. B、Just before midnight. C、During a security check. D、In the small hours of the morning. C

Kenyan police say one person was killed and 26 injured in an explosion at a bus station in central Nairobi. The blast hit a bus about to set off for the Ugandan capital Kampala. Last July, the Somali group al-Shabab said it was behind the blasts in the Ugandan capital which killed more than 70 people. Will Ross reports from the Kenyan capital.
The explosion happened beside a bus which was about to set off for an overnight journey from Nairobi to the Ugandan capital Kampala. Some eyewitnesses report that a bag was about to be loaded on board, but it exploded during a security check. Windows of the red bus were left smashed, and blood could be seen on the ground beside the vehicle. Just hours earlier, Uganda’s police chief had warned of possible Christmas-time attacks by Somali rebels.
1.  What is the news report mainly about?
2.  When did the incident occur?