Eric Zassenhaus/KPCC

The fire took almost two hours to extinguish completely.

DOWNTOWN LOS ANGELES — An early morning fire near Santee Alley in downtown L.A., damaged four businesses and injured one Los Angeles Fire Department captain, according to the fire department's website.

Firefighters arrived to 1025 Maple Avenue on Sunday to find a 50' x 100' building with black smoke pouring from the roof, says the LAFD. The structure was divided into four units, each of these stores sold an assortment of clothing and shoes.

Battalion Chief Joseph Klein said the fire may have started in a mezzanine area of one of the units and it is under investigation by the arson unit.

It took about 150 firefighters one hour and 41 minutes to completely extinguish the blaze.

During the firefight, a captain suffered a "significant avulsion" to the arm, fire officials report. Klein said something fell on the captain, broke through his gear and cut his arm on the inside -- barely missing a major artery.

The total monetary loss is still being calculated.