(CNN) An Iowa couple and their two children died from inhaling toxic gas while vacationing in Mexico, local authorities said.

The bodies of Kevin Wayne Sharp; his wife, Amy Marie Sharp; their son, Sterling, 12; and daughter Adrianna, 7, were discovered Friday at a rental condominium in the beach town of Tulum.

The family had been dead for about 36 to 48 hours, the Quintana Roo prosecutor's office said Saturday. Autopsies showed they suffocated after inhaling toxic gases.

Quintana Roo State Prosecutor Miguel Angel Pech told a local radio station that investigators discovered that "gas was escaping" from the apartment's hot water boiler, which he said could have been due to poor maintenance.

Pech also said that authorities expected conclusive results from autopsies within eight to 12 days that would indicate what type of gas led to the deaths.

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