Three Americans killed in militant attack on Kenyan military base used by US forces

One US military service member and two contractors have been killed during an attack by Somalia's Al-Shabaab militant group on a military base in Kenya, the US military said in a statement.

Two Americans from the Department of Defense 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.

The Al-Qaeda-linked group attacked the base, used by US and Kenyan military personnel, in Kenya's Lamu County.

Kenya Defence Forces (KDF) said the attack happened at around 5:30am and "an attempt was made to breach security at Manda Air Strip".

An image distributed by al Shabaab after the attack on a military base in Kenya shows a Somalia's al Shabaab militant holding the group's flag next to a burning aircraft (via REUTERS)

The bodies of four terrorist fighters have been found and the KDF confirmed the airstrip is now safe.

News of the deaths has come as three Katyusha rockets fell inside the Iraqi capital Baghdad's heavily fortified Green Zone, which houses government buildings and foreign missions, police sources told Reuters.

Sirens were being sounded and there were no immediate reports of casualties, the sources said.