Kenyan security forces on Thursday launched a manhunt in coastal Lamu County after suspected militants attacked a bus.
Lamu County Commissioner Irungu Macharia confirmed the fatalities and said three others injured in the attack were transferred to nearby health facilities.
Speaking to VOA, Macharia said police have yet to establish the identity of the attackers.
"There was that attack on the road, they attacked a bus along Malindi Lamu road, they fired at the bus and we lost three lives," he said. "That one you cannot verify until they claim responsibility, but as far as we know, they could be bandits or anybody else. They could also be those terror groups but we cannot say for sure who they were."
He said the bus that was attacked was accompanied by two other passenger buses, and had a police escort, hence the quick response by the security personnel.
"There was a bus that was ahead that was fired at, then they stopped two others, but the one that they shot at was the one that was leading the rest," Macharia said. "Then our officers came because the buses had escort, so when the officers responded to the distress, the attackers run away, but we are searching for them in the forest."
Macharia says the attackers numbered about 10.
Al-Shabab has claimed responsibility for previous attacks on vehicles traveling between Lamu and Mombasa. Most cars and buses using the road now travel with a security escort, which is a government requirement.
Macharia says the government is in pursuit of Thursday's attackers.
"We have an operation in the forest trying to see if we can get them, but at least operations on the road have returned to normal," he said. "We have escorted the buses and traffic is flowing."
Somalia-based al-Shabab has carried numerous attacks in Kenya over the past decade. The group says it is retaliating for Kenya contributing troops to the African peacekeeping force AMISOM in Somalia.
VOA's Swahili Service contributed to the story.