 -- Authorities have determined a fire that destroyed a Texas mosque was intentional but stopped short of calling it a bias crime, an official for the Bureau of Alcohol, Tobacco and Firearms and Explosives (ATF) said today.

On Jan. 28, the Victoria Police Department responded to a fire at the mosque just after 2 a.m. when a store clerk at a nearby convenience store noticed heavy smoke coming from the building, according to O.C. Garza, communications director for the city of Victoria.

The fire fully engulfed the building and caused an estimated $500,000 in damages, according to the Houston Field Division of the ATF.

It took firefighters about four hours to extinguish the blaze, which gutted the building and left only the outside facade of the mosque intact.

Although the fire was determined to be intentionally set, the evidence at this time "does not indicate the fire was a biased crime," the ATF said.

“Houses of worship are a sacred place in this country, and ATF is committed to devoting the necessary resources to solving this crime,” said Fred Milanowski, the special agent in charge of the ATF Houston Field Division.

“We are working closely with our local law enforcement and emergency service partners on this investigation and ask that anyone with information about this incident please report it.”

The ATF, along with the Victoria Islamic Center Mosque and Crime Stoppers, has offered a $30,000 reward for information leading to an arrest of the persons responsible, the ATF announced Wednesday.

Ibrahim Hooper, the National Communications Director for the Council on American-Islamic Relations, said CAIR is “obviously concerned” that the fire was determined to be intentionally set, because arson “can be an indicator of a bias motive.”

Hooper said that it may be easier to determine a motive once a perpetrator is apprehended.

The number of mosques targeted around the country increased to "unprecedented levels” since the presidential election in November, Hooper said, adding that CAIR plans to release a report in the near future that shows that 2016 may have been “the worst year ever in terms of the number of hate incidents targeting American mosques.”

The mosque did not have insurance, the president of the Islamic center, Shahid Hashmi, told ABC News days after the fire. A GoFundMe account set up for the rebuilding of the mosque had surpassed $1 million as of Wednesday.

The Islamic Center of Victoria hosted study groups for people with different religions so they would better understand Islam, a 23-year member of the mosque, Omar Rachid, told ABC News. Non-members would stop by the mosque to share a meal during Ramadan, and the mosque would also host a potluck dinner for Muslims and non-Muslims alike every Friday evening.

The congregation plans to rebuild the mosque at its current site, Hashmi said. The members will congregate in a mobile home next to the site in the meantime.

ABC News' Emily Shapiro contributed to this story.