Lamu , Manda, Kenya(ANN)-Somalia-based al-Qaeda-linked al-Shabaab militants on Sunday attacked a US-Kenya military base located in the coastal town of Lamu, the Kenyan military confirmed.

Kenyan defense forces announced it had successfully repulsed the attack, killing four militants, saying: “The airstrip is safe. Arising from the unsuccessful breach, a fire broke out affecting some of the fuel tanks located on the airstrip. The fire has been put under control and standard security procedures are now ongoing.”

Lamu County Commissioner Irungu Macharia confirmed the attack to Anadolu Agency, saying that the smoke, which “could be seen from all directions”, from the airstrip was put out, with military operations are “ongoing”.

The US Africa Command office also confirmed the attack, noting that the US Africa Command “acknowledges” that there was an attack on the Manda Bay Airfield, and that Kenya was monitoring the situation. “Al-Shabaab has claimed responsibility for the incident.”

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Al-Shabaab released a statement claiming the attack on the airfield, citing severe casualties and destruction to military vehicles – claims yet to be confirmed.

The Kenya Police report said two US helicopters and a Cessna aircraft had been destroyed as well as “multiple” American military vehicles. A Kenyan Cessna aircraft was also destroyed, it said.

Earlier, al-Shabab said in a statement the raid resulted in “severe casualties on both American and Kenyan troops stationed there”.

“The mujahideen fighters covertly entered enemy lines, successfully stormed the heavily fortified military base and have now taken effective control of a part of the base,” the armed group said.

Al-Shabaab claimed it had destroyed seven aircraft and three military vehicles, without providing other details. It also published pictures of masked gunmen standing next to an aircraft in flames.

The attack sent a dark plume of smoke into the air, Abdallah Barghash, a witness, told Reuters news agency. Barghash was among the crowds watching the drama unfold on Manda Island from neighbouring Lamu Island, a top tourist destination.

Al Jazeera’s Haru Mutasa, reporting from Kenyan capital, Nairobi, said it was an audacious attack by the armed group.

“The base is heavily fortified and al-Shabab still managed to break through. We are told the actual attack is over and that Kenyan and American forces are combing through the area trying to find those responsible,” Mutasa said.

“The area is near Boni forest where al-Shabab is thought to operate from. In the past, Kenyan security forces have been going in and out of that forest to try to weed out al-Shabab fighters,” she added.

This comes just a few days since al-Shabaab militants attacked a bus in the same area, killing three. The militants were later pursued by Kenyan forces, who managed to kill four of them.

Al-Shabaab militants have long carried out similar attacks in the Lamu County, located on the coast of Kenya, due to its proximity to the porous Kenyan-Somalian border.

In 2015, the militants killed more than 148 people in an attack on a university in the east of the country. Most of the victims were students.