CARACAS, March 28 (Xinhua) -- A prison riot and fire has broken out at a Venezuelan police station in the central city of Valencia and at least 68 people were killed, Venezuelan officials said Wednesday.

Chief Prosecutor Tarek William Saab said the dead, 66 men and two women, were visiting the prison overnight.

An investigation would be launched immediately to clarify what had happened, he said, adding that four prosecutors had already been assigned to the case.