Firefighters spray water on a fire at the Southwest Inn restaurant and hotel where at least four firefighters were killed, in southwest Houston May 31, 2013. [Photo/Agencies]

HOUSTON - At least four firefighters were killed while battling a hotel fire in the fourth largest US city of Houston on Friday, officials said.

A spokesperson for Houston Mayor Annise Parker said at least four firefighters have died, and five others were injured, making this one of the deadliest days in history for the Houston Fire Department, according to local TV channel ABC13.

The fire broke out at the Bhojan Restaurant about 12:09 pm local time and engulfed the neighboring Southwest Inn in southwest Houston, according to USA Today.

There was no immediate word on whether all 45 hotel guests, employees and others had been accounted for, the report said.

However, earlier media reports said all patrons and employees of the restaurant got out safely.

Video footage showed thick black smoke coming from building. The feeder road was closed to inbound traffic.

More than 100 firefighters were reportedly on the scene, and the Red Cross was also there providing assistance.

It was unclear what sparked the fire, according to reports.