Three sand harvesters have been buried alive after a dune collapsed at Kwa Muvai River in Makueni County.
Two more harvesters were rescued from the debris and rushed for treatment.
The accident occurred at 5am, according to Makueni County Commissioner Mohammed Maalim.
"Those neighbouring the scene reported hearing a bang at the mine (sic) and on rushing there, they found that the mine had caved in, burying the five alive," he said.
He cautioned sand harvesters against working in dunes and rivers at night, saying it is against county laws on sand harvesting.
Further, Mr Maalim said police would impound a sand transporter's lorry that was trapped at the collapsed dune.
"The lorry will be placed in the hands of authorities to assist in investigating this incident," he said.
Although the government has outlawed commercial sand harvesting in the area, the activity happens clandestinely.