NAIROBI, Kenya -- An explosion in a highly populated area of downtown Nairobi on Sunday killed one person and injured at least 29 people, and officials said an investigation is under way to determine if the blast was caused by terrorism.

Prime Minister Raila Odinga said it was too early to tell if the blast in Kenya's capital was terror related.

Omar Alwiya, a bus conductor, said he was sleeping when he heard an explosion that shook the room he was in and filled it with dust. He rushed to the scene and found two shipping containers overturned, several cars destroyed and a fire at a gas station. He said he then went to check on his sister who lives in a building opposite the blast site and found that two of her children had been injured by shattered glass.

A nurse at the Guru Nanak hospital in Nairobi said one of two people admitted at the hospital died from deep burn wounds. The nurse spoke on condition of anonymity because she is not authorized to speak to the press.

Dr. Peter Kamau Wanyoike said 29 people were admitted to Kenyatta National Hospital. Nine had burns on 60 percent of their body. Others were injured by falling glass or minor burns.

Charles Owino, a deputy police spokesman, said police are investigating all possible causes for the blast, including terrorism.

Kenya has been on high alert since the killing of Osama bin Laden because of threats from al-Qaida-linked al-Shabab militants who operate in neighboring Somalia.

The group has threatened to attack Kenya for allegedly helping Somali government troops and their allies attack the militants' bases in Somalia.

Al-Shabab -- Somalia's most dangerous militant group -- claimed responsibility for the double suicide bomb attack in Uganda's capital in July during the World Cup final. The blasts killed 76 people.

Sunday's explosion in downtown Nairobi tore through the busy Kirinyaga road, a street full of automotive part shops and mechanics plying their trade in open spaces. At the explosion site, a metal container was mangled and another flipped over by the blast. Vehicles were destroyed by the impact and tires were punctured. A five story building next to where the blast occurred had all its windows shattered.

Alwiya said a petrol station was on fire by the time he got to the blast site and if it was not for the quick response of the Kenyan fire fighters, who put out the fire, its fuel storage tanks might have caught fire leading another explosion.