SAN MARCOS, Texas -- Multiple agencies have completed the on-scene portion of the investigation into the deadly fire at Iconic Village and Vintage Pads apartments.

The San Marcos Fire Department, Bureau of Alcohol, Tobacco, Firearms and Explosives, San Marcos Fire Marshal, San Marcos Police Department and State Fire Marshal’s Office all assisted in the investigation, as well as surrounding city fire departments.

The National Response Team has determined the origin of the fire, but still does not have a final classification.

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Fire Marshal Kelly Kistner said the building was built in the 1970s when sprinkler systems were not required by law, and there have since been no major renovations. Kistner said that Texas Property Code states a landlord must have smoke alarms installed in every unit.

"The apartment management does have their smoke alarms installed in accordance with the Texas Property Code. Through all of our observations that we have made, we do not see where there would've been any deficiencies with the smoke alarms as they would've needed to be installed," Kistner said.

He said there's no frequency set by fire departments for how often the smoke alarm inspections have to be completed.

"So there's no standard, there's no law for how frequent those have be done. The property owners are required to check smoke alarms upon a new tenant moving in, and so that's when they're supposed to do it and make sure they're done. In this case, we know that it's done more frequently because of information and records provided to us by the property management company,” said Kistner.

The final classification of the fire - whether it is due to natural causes, accidental, incendiary or ruled undetermined - will be announced in the coming weeks after more testing and analysis.