Pentagon spokesman Jeff Davis said the US was looking into reports that Somali forces were killed.
A Somali intelligence official meanwhile said Somali elite forces supported by US warplanes had conducted a raid on an al-Shabaab-controlled village in the south early Thursday, killing three Islamists including a middle-level commander.
The operation targeted Gole-shumbi village 60 kilometres west of the port city of Kismayo, said the official, who asked to remain anonymous.
The US supports Somalia in its military campaign against al-Shabaab. Thousands of lives have been lost on both sides over a decade of unrest.