A trailer plunged into the Indian Ocean at the Likoni crossing channel early on Wednesday morning, reports say.
Witnesses say the driver of the trailer lost control as he tried to maneuver into the ferry. He was headed to Mombasa.
Witnesses said the trailer was hauling maize from Tanzania although the exact quantity remains unknown.
No injuries had been reported as of the publishing of this report but the incident caused a heavy snarl-up at the ferry as ferries could only dock on one side.