A grenade blast in Kenya's capital city of Nairobi killed one person on Friday, the day before U.S. Secretary of State Hilary Clinton is scheduled to arrive as part of her seven-nation African tour.

Early reports from the Associated Press suggest that the assailant was attempting to throw the grenade at a group of soldiers outside of a military base, but was killed himself when the explosive went off too soon. Nine bystanders were injured, and an investigation into the incident is ongoing.

Nairobi has suffered a string of fatal attacks over the past year, many of which are tied to the Islamist terrorist group al-Shabab. The insurgents, based in neighboring Somalia, and their sympathizers have ramped up attacks in Nairobi following Kenya's decision to send troops into Somalia to combat and contain al-Shabab.

No group has yet claimed responsibility for Friday's attack.

Clinton's visit is intended, among other things, to strengthen the security ties between Kenya and the United States. Al-Shabab and related militant movements are expected to be a topic of discussion during Clinton's Saturday meetings with Kenyan President Mwai Kibaki and Prime Minister Raila Odinga.