One member of the US military and two contractors were killed on Sunday after an attack by Somalia’s Al Shabab terrorist group on a military base in Kenya, the US military said in a statement.
The statement added that two Americans from the Department of Defence were also wounded in the attack.
"The wounded Americans are currently in stable condition and being evacuated," the US military's Africa Command said in a statement.
Earlier on Sunday, Al Shabaab extremists attacked Kenya and US military base, destroying several American aircraft and vehicles.
A US Africa Command statement, issued after Al Shabab released photos of blazing aircraft, said “an accountability of personnel assessment is underway” at the Manda Bay airfield, close to the Somali border. Kenyan military spokesman Paul Njuguna said five attackers were dead.
In a statement on Sunday evening, Al Shabab said the attacks had left 17 US “casualties,” nine Kenyan soldiers killed and seven aircraft destroyed.
"Seven aircraft and three military vehicles were destroyed in the attack," Al Shabab said in a statement in which it claimed responsibility for the assault.
Major Karl Wiest from Africom said fewer than 150 US personnel were at the base, where they provide training and counter-terrorism support to East African partners.
"Initial reports reflect damage to infrastructure and equipment. An accountability of personnel assessment is under way," Africom said in a press release.
The assault that began before dawn lasted about four hours, witnesses and military sources said.
Kenyan military spokesman Col Paul Njuguna said the base was now secure.
Kenya sent troops into Somalia in 2011 after a spate of cross-border attacks and kidnappings. They were later absorbed into an African Union peacekeeping force, now 21,000-strong, that supports the shaky, Western-backed Somali government. Al Shabab has been fighting for more than a decade to overthrow the government and impose strict Islamic law.
Independent investigator Benjamin Strick, who analyses satellite imagery for open source investigation websites such as Bellingcat, said the photos of gunmen next to a burning plane published by Al Shabab matched satellite images of buildings and a distinctive aircraft apron adjacent to the base but outside its perimeter.
Residents on nearby Lamu Island, a haven for wealthy tourists and visiting European royalty, say a loud explosion jolted them awake before 4am. Abdalla Barghash said he later saw a large dark plume of smoke rising from the Manda Bay mainland, where the airstrip and base are located.
Resident Omar Ali said he was on the way to his farm when he heard a huge bang and saw smoke. Fellow farmers reported sustained gunfire, he said. The gunfire was still going on four hours later, a military source said.
Lamu county, which is far more impoverished than the island, is frequently targeted by Al Shabab with roadside bombs and ambushes on travellers or attacks on isolated villages. The insurgents killed three passengers when they attacked a bus in the county on Thursday.
The group carried out a similar raid in September on Baledogle base in Somalia, which is used by both Somali special forces and American troops. All the attackers were killed and the base was not breached.
It comes nearly a year after Al Shabab launched a deadly suicide attack on an upscale hotel and office complex in the Kenyan capital Nairobi, killing 21 people.