Investigators are asking for public assistance in uncovering what caused a fire that destroyed one of El Paso's oldest buildings Thursday evening.

Detectives spent Friday morning interviewing nearby business owners about the fire in the old John Hardin law offices, and building inspectors toured surrounding buildings looking for fire violations, but it's still unclear if the fire was accidental or intentional. San Antonio Avenue and El Paso Street were taped off Friday afternoon as investigators dug through the rubble, treating the scene as an arson case to avoid compromising any potential evidence if the fire was set intentionally, according to El Paso Fire Investigator Nick Torres.

A number of agencies were on scene Friday trying to find more answers for the investigation, including El Paso Electric, the Bureau of Alcohol, Tabaco, Firearms, and Explosives, the El Paso Fire Department, and the El Paso Police Department. Police spokesman Javier Sambrano said police officers will keep the streets closed through the weekend as demolition crews remove what's left of the historic building, constructed in 1883.

If you have any information, you can contact the El Paso Fire Department at (915) 832-4439.

The fire started just after 6:30 p.m. Thursday evening, according to El Paso Fire Department spokesman George De La Torre. Fire crews worked to place the fire under control, but the fire quickly spread to the second and third floors. No one was injured but the building is a complete loss. Fire crews demolished the second and third floors to prevent a collapse after the fire weakened the building's infrastructure.