NAIROBI, Kenya -- A police officer in a central Kenyan town went on a shooting rampage, killing 10 people in three different bars, officials and a local journalist said Sunday.

The shooting spree happened late Saturday in Siakago, 90 miles northeast of the capital, Nairobi.

Officials are investigating the shootings, said Provincial Police Chief Marcus Ochole. He confirmed that 10 people had been killed but said he couldn't immediately provide details.

John Chelimo, the district commissioner, said the suspect, who he said was in his 30s, went out Saturday night looking for a female friend but that he couldn't find her. The officer is in police custody, Chelimo said.

"He has not talked and the motive is not clear," Chelimo said.

A local radio reporter, Antonin Newite, said the police officer opened fire in three different bars, killing one person in each of the first two bars and eight people in the third bar.

Many townspeople didn't realize what was happening because they mistook the gunfire for fireworks, said Newite. Many Hindus in Kenya were celebrating the festival of Diwali on Saturday.

The killings sparked a mass protest in front of the Siakago police station early Sunday, said Nyaga Manunga, whose daughter was one of those killed. He said the shootings took place very close to the police station.

"In Siakago there is no security," Manunga said. "Someone can't just shoot 20 to 30 bullets without any reaction from the police."