Operation Linda Boni Chief James ole Serian has denied reports that al Shabaab militants attacked Mokowe GSU camp in Lamu West on Tuesday morning.
According to earlier reports, the attack took place at about 1am.
The incident is said to have occurred just hours after President Uhuru Kenyatta ordered police to eliminate them.
"There was no attack in Mukowe town last night," Mukowe said in a statement.
"After investigating the matter, it was found that a sentry at the GSU camp heard suspicious movement near the camp gate and decided to fire as the precautionary measure.
"It should be clearly noted that there was no exchange of fire between security officers and any enemy."
Serian said all security officers were alerted and that their teams and others in charge of Lamu security held a meeting after the incident.