NAIROBI, Kenya -- Kenyan police said Tuesday that a blast that injured more than 30 people in a Nairobi shopping center the day before was caused by a homemade bomb, following reports that a suspicious bag was left at the scene just before the attack.
Police had initially blamed faulty electrical wiring for the blast about 1:15 p.m. But on Monday, Prime Minister Raila Odinga had already voiced the fears of many Kenyans when he called the blast a terrorist attack.
One witness told local media that she saw a man come into a shop several times in the area where the attack occurred. She saw him leave a bag and quickly depart, minutes before the blast.
"He came into the shop twice, looking at T-shirts," Irene Wachira, the witness, told Reuters news service. "He said he didn't have money so he left. Then he came back. He left a bag and a few moments later we had an explosion. The roof caved in and debris started falling on us."
Police spokesman Eric Kiraithe told a news conference on Tuesday that police were trying to trace two male suspects. He said forensic analysis was underway to determine what explosives were used in the attack. Police officials told local media that the blast may have been caused by a fertilizer bomb.
Kenyan media reported Tuesday that FBI agents were at the scene of the blast on Moi Avenue helping with the investigation.
Since invading Somalia in October in a bid to crush the Somali militia Al Shabab, Kenya has seen a series of grenade attacks in crowded areas such bus terminals, killing dozens of people. The rebel group threatened to blow up Nairobi skyscrapers.
However, no group took immediate responsibility for Monday's bombing.
Witnesses described a scene of chaos at the site of the blast.
Geoffrey Kiarie, 22, said that from an electronics shop near the blast he heard a loud explosion before his shop filled with smoke. Then he heard people screaming.
"The screams were very desperate and we all ran out," Kiarie told The Times. "We rushed to the scene and started helping people out. What I saw was very disturbing.
"Some people were thrown on the floor with cuts on their faces, hands and on parts of their bodies," he said. "I saw someone without clothes, screaming saying he was outside on the street and was lifted high and banged down hard. His clothes were torn into pieces and he had a bad head injury as if he was hit by blunt object."
On Monday, Odinga said his people would stand firm against terrorism.
"Kenyans will not be cowed, Kenyans will not surrender to terrorists," he said at the scene of the blast.