CANCUN, Mexico - Prosecutors in Mexico said Monday they have filed charges against five contractors and employees at a Caribbean coast hotel where a Nov. 14 explosion killed five Canadian tourists and two Mexicans.

Rodolfo Garcia Pliego, the assistant attorney general of Quintana Roo state, where the hotel is located, said investigators found an unauthorized extension of a gas line under the hotel lounge where the blast occurred.

Rodolfo Garcia Pliego says the gas line at the 676-room Grand Riviera Princess resort in Playa del Carmen, south of Cancun, was not reported to authorities, and not properly installed or maintained.

The charges against the five announced range from homicide and causing injuries, to professional or technical misconduct, charges that presumably apply to the installers.

Officials had earlier blamed an accumulation of swamp or sewage gas, but later determined the line was the cause.

Garcia Pliego said Monday the charges were filed Friday and that prosecutors have requested arrest warrants for the suspects.

A leak from the heating-gas line, apparently meant to fuel a pool heating unit, may have been set off by a spark from an electric switch or plug.