Al Shabaab militants have launched a 4am attack on the Manda-Magogoni US-Kenya naval base in Lamu County Sunday morning.
Daily Nation reports that heavy exchange of gunfire is ongoing.
Lamu County Commissioner Irungu Macharia confirmed the attack on the Manda Bay base.
The raid comes days after three people were killed in a bus attack by al Shabaab near the Somalia border.
Two others were injured when the bus travelling from Mombasa was targeted in Lamu county as heavily armed men sprayed it with bullets.
Kenya has troops in Somalia supporting the UN-backed government in its fight against al-Shabab.
The country has been on high alert over the Christmas and New Year holiday period, following intelligence reports that al-Shabab could carry out attacks.
Lamu or Lamu Town is a small town on Lamu Island, which in turn is a part of the Lamu Archipelago in Kenya.
Situated 341 kilometres by road northeast of Mombasa that ends at Mokowe Jetty, from where the sea channel has to be crossed to reach Lamu Island.