ALGIERS - Four foreign hostages were freed on Thursday by Algeria's armed forces, the official APS news agency said, giving no further details.A local source has told Reuters six hostages were killed when a vehicle was fired upon by the military. A separate source, in the security services, said earlier that 25 foreigners had escaped. Gunmen said they were initially holding 41 foreign hostages after they stormed a gas plant in the remote Algerian desert on Wednesday morning.