The boda boda operator and his two passengers were killed when gunmen opened fire on the bus and a police escort car.
The bus was heading to Kipini from Malindi.
An occupant of a station wagon and a lorry driver were killed when their vehicles were sprayed with bullets in Gamba near Nyongoro On August 30.
The attackers also bombed and destroyed an electric pylon belonging to Kenya Power.
Earlier on August 18, four people were beheaded by suspected al-Shabaab militants at Maleli Village in Witu.
And on November 28, two AP officers died while three others were wounded when their vehicle was ambushed at Lango La Simba in Nyongoro, on the Lamu-Malindi road.
The policemen were escorting five buses from Lamu to Mombasa.
The increase in the deadly raids led Coast regional coordinator Nelson Marwa to call for the bombing of Boni Forest.
The administrator said al-Shabaab members had turned the woodland “into a playground, launching attacks on security personnel and civilians at will”.
Despite bombing some parts of the dense forest and destroying a number of militia camps, the attacks did not stop.
Recently, details emerged on the group’s new operational tactics.
Officials said the terrorists were using women as spies in areas targeted for attacks.
Security officers in Galmaghala, Ijara, Bodhei, Milimani, Basuba, Mararani, Ishakani and Kiunga villages said they had no option but to send women out of the villages.
Police, administrators and military chiefs have, in the meantime, expressed confidence they will emerge victorious in their war against al-Shabaab.
In a recent interview, Coast Police Commander Larry Kieng said efforts were in place to ensure the fighters were dealt with.
“We have been grappling with the problem but we need cooperation from residents, especially those in Boni and its surroundings,” Mr Kieng told the Nation.
“We are here to ensure the region is safe and we will do that by all means.”
Despite the assurances, some security agents deployed to fight the group have complained of lack of proper equipment and provisions.
Some officers who lost their lives were travelling in armoured personnel carriers, vehicles that were meant to be bullet proof and able to withstand road mines and other explosives.
Lamu residents hope security forces will be more successful in their bid to defeat the terrorists this year.