Texas authorities are investigating a Christmas Day fire at a Houston mosque, which is believed to have been set intentionally. Investigators upgraded the investigation to "incendiary" and cited multiple points of origin in the fire as suspicious.

"As part of the investigative process, evidence is being collected and analysed; and interviews are being conducted," Houston Fire Department (HFD) said in a statement on 27 December. "We want to reassure the public that we will conduct a complete and thorough investigation."

HFD spokesman Ruy Lozano told the Houston Chronicle that the Bureau of Alcohol, Tobacco and Firearms is assisting in the investigation. According to the Chronicle, it took around 80 firefighters to extinguish the two-alarm fire that started at about 2.45pm. Mosque members told reporters that images from surveillance cameras at the centre of worship was turned over to authorities.

The extent of the damage to the mosque has not been revealed, however, investigators said neighbouring businesses in the shopping centre were damaged by heavy smoke, KHOU reported. On 26 December, mosque members were forced to pray in at a different location in the same shopping centre.

Democratic Representative Sheila Jackson Lee condemned the attack and vowed to follow up with the investigation. "Attacking a place of worship is a despicable act," she said. "I will continue to closely monitor the possible criminal investigation and the safety of the members of the Mosque. Our faith in humanity will not be intimidated and we stand together against any form of violence towards the innocent."

On the night of 25 December, the Council on American-Islamic Relations called on law enforcement to consider a "possible bias motive" for the blaze. "Because of the recent spike in hate incidents targeting mosques nationwide, we urge law enforcement authorities to investigate a possible bias motive for this fire," Mustafaa Carroll, director of the local CAIR chapter, said. Meanwhile the Islamic Society of Greater Houston called on parishioners not to spread rumours about how the fire potentially started. The society promised to help rebuild the mosque as soon as possible, KHOU reported.

No arrests have been made, authorities said.