Four civilians including a child were shot dead on Tuesday as suspected Al-Shabaab Islamists attempted to attack a telecommunications mast in eastern Kenya near the Somali border, police said. Two of the attackers were also killed by police.Kenya is on high alert after the Al-Qaeda linked group on Sunday stormed onto a US military base in the coastal Lamu region, destroying several aircraft and killing three American citizens.Three Kenyans were arrested later on Sunday for allegedly trying to force their way into a British military camp in central Kenya, although the British army later said in a statement they did not believe there was a "direct threat".Police spokesman Charles Owino said that more than 10 attackers had attempted to destroy the mast on Tuesday morning, two of whom were shot dead.READ | Five killed in jihadist attack on Somali hotel, al-Shaabab claims responsibilityA separate police statement said the attack took place in the town of Saretho, 25km from the Dadaab Refugee Camp - where Al-Shabaab has been found to be operating in the past."The criminal gang had targeted the nearby communication mast and in the process four innocent lives were lost, including that of a teacher and small child," read the statement.Police said two AK47 assault rifles, materials to make improvised explosive devices and other "crude weapons" were discovered."Security agencies have been mobilised and are pursuing the rest of the attackers."ALSO READ | Kenyan army attacked telecom towers in Somalia: UNThe Islamists began targeting Kenya after it sent troops into Somalia in 2011 to join an African Union peacekeeping force seeking to combat the militants who have been trying to topple an internationally-backed government in Mogadishu for over a decade.Al-Shabaab has in the past carried out bloody sieges against civilians in Kenya, such as the upmarket Westgate Mall in 2013 and Garissa University in 2015.The uptick in tensions comes just days before the one-year anniversary of an attack on a Nairobi hotel complex which left 21 people dead.