The crash of a military helicopter in Kenya, near the border with Somalia, killed at least eight people, officials said Tuesday.

The cause of the accident in Lamu County, on the Kenyan coast, was not immediately clear. Kenyan defense forces operate in the region to help deter al-Qaeda- linked extremists from the Al-Shahab group, based across the border in Somalia.

The Defense Ministry said the Air Force helicopter crashed during a night patrol. A commission of inquiry was sent to the scene. A defense official and a police official said all military personnel and crew members aboard the helicopter had died.

Kenyan troops are also present in Somalia as part of the African Union Transitional Mission in Somalia to help fight Al-Shabab. Kenyan forces deployed to Somalia in 2011, but there are now plans to withdraw multinational forces as Somali troops take over their country's security.

Al-Shabab has increased attacks in Kenya in recent months, killing dozens of people in the border region, as the extremists feel pressure from a Somali military offensive launched last year.