Kisumu County police commander Karanja Muiruri said the victims, a man and his wife, died during the blast on Tuesday evening in the Nyakach area while the attacker also died on the spot after detonating himself.

Muirui said the terror suspect, identified as Joseph Odhiambo Ondiek alias Pope, went to the couple's homestead and found them seated with their daughter and started to question them.

"The al-Shabab suspect started questioning them on things they don't understand," he said.

The police said an improvised explosive device that the terror suspect was carrying suddenly detonated killing the suspect on the spot and the couple while the couple's daughter sustained injuries and is hospitalized.

The police said the 44-year-old suicide bomber was suspected to be a returnee from the al-Shabab terror group which has increased attacks in the East Africa region.

Muiruri said security agencies have launched an investigation into the Tuesday evening incident that he termed an act of terrorism.

"We are trying to establish where he has been for the past months. This is serious and we are pursuing it," he said.

According to the police report, area residents identified the suspect who on December 17 last year tried to kill his girlfriend in their rented house at Katito town over alleged infidelity. The suspect had made an explosive and left it in the house. It exploded but the girlfriend escaped unhurt.

"After the Katito incident, the suspect disappeared to an unknown location just to resurface on Tuesday to attack people. Tuesday's incident is taken to be an act of terrorist," the police said in the report.