The mine has been the scene of increasing violence for the past week as a result of an illegal strike by rock drill operators and a dispute between rival unions.
The dispute had already claimed the lives of eight Lonmin workers and two policemen but with an increased presence of the South African police services at the site, the confrontation erupted after police were surrounded by rioters carrying machetes and sticks.
A Lonmin announcement said the company welcomed the increased police presence and was cooperating fully with authorities to help restore a safe and secure environment for its employees as quickly as possible.
"The striking rock drill operators remain armed and away from work," it said.
Witnesses said the striking miners had been warned by police that they would take action, supported by armoured vehicles and barbed wire barricades, after talks with the militant Association of Mineworkers and Construction Union had broken down.
The violence started on Sunday when two Lonmin security guards were killed and six injured as a large group tried to attack Lonmin facilities.
On Monday two policemen and further three Lonmin employees lost their lives while another policeman and an employee were injured as the violence continued.
Lonmin was forced to close its South African operations, causing a rise in global platinum prices to $US1435.20 per ounce, up 2.8%, although it did state that the shafts remained operational in readiness for production when employees returned to work.
Lonmin is listed on the London Stock Exchange and the Johannesburg Stock Exchange and is one of the world's primary producers of platinum group metals.